FRR - Final Report

This report summarizes three years of IFPRI-supported research on cohesive powder flows and deagglomeration processes. The project’s primary objective was to investigate the drying of cohesive granular materials, specifically focusing on strategies to minimize salt deposits on dried powders. Over this period, we developed several lab-scale experimental approaches for both testing agglomerate fragmentation and characterizing cohesive powders. We detail insights ranging from the development of drying and fragmentation processes to the fundamental mechanics of bulk- and capillary-scale cohesion, alongside quantitative results from specialized techniques used to analyze these flows.

Objective: This project aimed to advance the fundamental understanding of powder flows by developing model cohesive granular materials and characterizing their rheological behavior to improve powder manipulation in industrial processes. The primary focus was to tune adhesive forces, develop original experimental setups to characterize particle interactions, and design a shear cell capable of investigating inertial rheology at low pressure. The ultimate goal was to provide physical insights into flowability, with applications in processes such as aeration, compaction, and industrial handling.

Key Achievements:

• Development of Model Materials: Successfully created model cohesive particles with tunable adhesion, using polymer coated silica and functionalized polymer particles. Demonstrated the ability to control adhesive properties, enabling systematic studies of cohesion effects.
• Characterization of Particle Properties: Developed experimental techniques to measure interparticle adhesion and friction. Identified a lubrication transition in large particles, characterized through tribological measurements at the particle scale.
• Bulk Rheology Measurements: Designed and implemented a novel shear cell capable of measuring the rheology of _ne particles under low confinement stresses and in the inertial regime. Achieved the first measurements of constitutive laws under low confining stress, revealing unexpected behaviors such as shear weakening and pressure-dependent transitions.
• Study of Flow Configurations: Initiated investigations into ow configurations relevant to industrial processes, including compaction and drag/lift forces in cohesive materials. Observed that lift forces are signficantly more sensitive to cohesion than drag forces, suggesting potential new methods for powder characterization.

Challenges and Limitations:

The study of air-particle coupling, a critical aspect of powder dynamics, was not addressed due to time constraints and the complexity of designing appropriate experimental tools. Some objectives, such as the systematic study of ow configurations, remain preliminary and require further investigation.

Impact and Future Directions:

This project has laid the groundwork for a deeper understanding of cohesive granular flows, with implications for industrial processes involving powders. The development of model materials and advanced experimental techniques opens new avenues for studying the interplay between adhesion, friction, and ow dynamics. Future work will focus on refining measurements to reveal the control parameters of the powder rheology, and extending findings to a broader range of industrial applications.

Conclusion:

This project has made signficant progress in developing innovative tools to characterize cohesive granular materials, both at the particle scale and in terms of bulk properties. We have begun to gain valuable insights into the behavior of powders under low confinement and inertial conditions. While challenges remain, particularly in fully understanding the role of air-particle interactions and refining ow configurations, the findings provide a robust foundation for future research, with direct relevance to the industrial characterization and handling of powders.

Experimental and Theoretical Study on Atomization Process

We present the results of an experimental and theoretical study on the atomization process of high viscosity and polymeric fluids. We have developed a model for the atomization process in swirl and fan nozzles. The primary atomization in such nozzles results in the formation of filaments and long ligaments, which breakup into droplets.

Primary Atomization Model

We propose a primary atomization model based on the interaction of two breakup mechanisms: the growth of surface wave and the formation of perforations. At the nozzle orifice, small scale surface waves are formed due to a high relative velocity between the liquid sheet and ambient gas. As the surface waves grow, the liquid sheet forms alternating thick and thin regions due to the nonlinearity of the surface wave. The thin region becomes thinner as the sheet expands and perforations appear.

As these perforations expand, streamwise filaments form as the boundaries of these perforations approach each other. Close to the breakup position, the growth of these perforations will eventually be stopped by the thick regions on the liquid sheet. As these streamwise filaments detach from the liquid sheet, the liquid sheet breaks up and forms filaments.

Types of Filaments

As a result, there are two types of filaments formed:

• The thin streamwise filaments formed from the breakup of thin regions due to perforations.
• The thick spanwise filaments formed from the thick regions due to the surface wave.

These filaments become thinner due to the lateral velocity and eventually these two types of filaments break up into droplets due to surface waves and form the spray with a wide range of droplet sizes. Theoretical models are developed to predict the droplet size distribution for this breakup for both Newtonian and Viscoelastic fluids.

The objective of this research project is to assess and enhance the ability of a recently-advanced high-fidelity modeling framework for spray formation to model complex liquid break-up and predict drop size distributions in high viscosity and non-Newtonian liquid atomization systems, such as found in spray drying applications. This framework, dubbed enhanced Volume of Fluid (eVOF), was developed by the PI’s research group and hinges on two key components:

1. a fully conservative Eulerian interface capturing technique with the ability to capture sub-grid scale liquid features such as thin films and thin ligaments, known to be of critical importance in the break-up of viscous and non-Newtonian fluids, and
2. simple physics-based break-up models to convert these thin liquid features into spray droplets that can be tracked in a Lagrangian fashion.

In this project, non-Newtonian constitutive models were implemented and tested in the PI’s research flow solver, and shown to influence spray formation in simple flow configurations. Moreover, a simple pressure-swirl configuration was explored to demonstrate the ability of eVOF to preserve thin liquid films and virtually eliminate numerical break-up. Following this, the non-Newtonian constitutive models were further refined and validated against bubble rise experiments and deployed in complex simulations. A realistic pressure-swirl nozzle was selected for study based on availability of nozzle geometry and drop size measurements. Despite the complexity of the resulting flow, eVOF was again shown to preserve sub-grid scale liquid films successfully. Advances were made on sub-grid scale modeling of film and ligament break-up, allowing preliminary comparisons of drop sizes against experiments to be shown. Finally, a cylindrical reconstruction method was demonstrated for capturing ligaments at the sub-grid scale, which offers avenues for increased simulation accuracy for non-Newtonian and high-viscosity cases.

Going forward, the sub-grid scale modeling of film and ligament break-up will be further improved, in particular in the limit of high-viscosity liquids, and a more comprehensive comparison of drop sizes will be made against experiments.

The main objective of this project was to apply an innovative pneumatic nozzle design, the Air-Core-Liquid-Ring (ALCR)-nozzle, for spray-drying of highly viscous liquids and pastes. The project is divided into three main working packages (WP). WP 1 aimed to validate the ACLR atomizer technology to enable spraying of highly viscous liquids, using both experimental measurements and CFD simulations. WP 2 aimed to evaluate the impact of the composition and morphology of the atomized droplets on the drying kinetics, for highly concentrated feeds. WP 3 aimed to join the results of both packages to investigate the applicability of the ACLR nozzle for spray-drying of highly viscous liquids. The project schedule is shown in Fehler! Verweisquelle konnte nicht gefunden werden.. This is a short overview of the main findings of the project:

WP 1: Atomization with the ACLR nozzle

• The ACLR can achieve stable atomization with feed viscosities as high as 3 Pa·s, at relatively low pressures (7 bar) and low air-to-liquid ratios (0.8).
• The internal flow and the external spray instabilities are directly correlated.
• A CFD model was successfully adapted in STAR-CCM+ v.2206 to predict the internal flow of non-Newtonian maltodextrin solutions being atomized with an ACLR nozzle. In general, the predicted ALRs from the simulations agree with experimental results. Additionally, the liquid lamella thickness inside the nozzle follows the same trend in simulations and experiments: A smaller internal lamella variation is observed as the ALR increases.
• The possibility of using simulations to evaluate operating conditions outside of experimental capabilities was evidenced. The lamella variation can be severely reduced by increasing the operating pressure to 15 bar, which is still far below the 50-250 bar that is common in pressure swirl nozzles.

WP 2: Evaluation of the impact of the composition and morphology on the drying kinetics and model development by single droplet drying

• A method for the analysis of the mass data and calculation of the drying kinetics was developed in a single droplet drying (SDD) setup.
• The impact of the drying temperature was evaluated. While the impact of the drying temperature on the drying time agrees well with expectation, its influence on the drying kinetics showed no apparent trend.
• Experiments were conducted to evaluate the impact of initial solids concentrations up to 53 wt%. The results for the particle size, mass and drying kinetics showed good agreement with theoretical considerations. Looking at the drying time, it was revealed that the impact of lower water contents and lower water flux seem to level out at constant droplet size for higher solids concentrations.
• The results showed a significantly shorter time to the locking point for higher dry matter concentrations, reducing the risk of powder stickiness.

WP 3: Proof-of-concept of industrial applicability of the ACLR nozzle for spraydrying of highly viscous liquids

• The numerical investigation for an optimized nozzle design identified that a shorter outlet length, a larger mixing chamber inclination, and rounded internal edges lead to thinner and more stable liquid lamellas.
• Two improved nozzle designs were proposed, and the one with the shortest outlet length (0.8 mm) was shown to consistently produce the thinnest and most stable lamellas.
• The optimized nozzle demonstrated consistent performance improvements, leading to thinner lamellas and smaller droplets compared to the original design in both simulations and experimental tests.
• The improved design highlights significant potential for energy consumption and operating cost reductions, as it outperformed the original nozzle even when operating at lower pressures and air-to-liquid ratios.
• Optimized ACLR nozzle design leads to 33 % smaller spray droplets (x90,3) compared to the initial (basic) design.
• has been elucidated in WP 2.

The main objective of this project was to apply an innovative pneumatic nozzle design, the Air-Core-Liquid-Ring (ALCR)-nozzle, for spray-drying of highly viscous liquids and pastes. The project is divided into three main working packages (WP). WP 1 aimed to validate the ACLR atomizer technology to enable spraying of highly viscous liquids, using both experimental measurements and CFD simulations. WP 2 aimed to evaluate the impact of the composition and morphology of the atomized droplets on the drying kinetics, for highly concentrated feeds. WP 3 aimed to join the results of both packages to investigate the applicability of the ACLR nozzle for spray-drying of highly viscous liquids. The project schedule is shown in Fehler! Verweisquelle konnte nicht gefunden werden.. This is a short overview of the main findings of the project:

WP 1: Atomization with the ACLR nozzle

• The ACLR can achieve stable atomization with feed viscosities as high as 3 Pa·s, at relatively low pressures (7 bar) and low air-to-liquid ratios (0.8).
• The internal flow and the external spray instabilities are directly correlated.
• A CFD model was successfully adapted in STAR-CCM+ v.2206 to predict the internal flow of non-Newtonian maltodextrin solutions being atomized with an ACLR nozzle. In general, the predicted ALRs from the simulations agree with experimental results. Additionally, the liquid lamella thickness inside the nozzle follows the same trend in simulations and experiments: A smaller internal lamella variation is observed as the ALR increases.
• The possibility of using simulations to evaluate operating conditions outside of experimental capabilities was evidenced. The lamella variation can be severely reduced by increasing the operating pressure to 15 bar, which is still far below the 50-250 bar that is common in pressure swirl nozzles.

WP 2: Evaluation of the impact of the composition and morphology on the drying kinetics and model development by single droplet drying

• A method for the analysis of the mass data and calculation of the drying kinetics was developed in a single droplet drying (SDD) setup.
• The impact of the drying temperature was evaluated. While the impact of the drying temperature on the drying time agrees well with expectation, its influence on the drying kinetics showed no apparent trend.
• Experiments were conducted to evaluate the impact of initial solids concentrations up to 53 wt%. The results for the particle size, mass and drying kinetics showed good agreement with theoretical considerations. Looking at the drying time, it was revealed that the impact of lower water contents and lower water flux seem to level out at constant droplet size for higher solids concentrations.
• The results showed a significantly shorter time to the locking point for higher dry matter concentrations, reducing the risk of powder stickiness.

WP 3: Proof-of-concept of industrial applicability of the ACLR nozzle for spraydrying of highly viscous liquids

• The numerical investigation for an optimized nozzle design identified that a shorter outlet length, a larger mixing chamber inclination, and rounded internal edges lead to thinner and more stable liquid lamellas.
• Two improved nozzle designs were proposed, and the one with the shortest outlet length (0.8 mm) was shown to consistently produce the thinnest and most stable lamellas.
• The optimized nozzle demonstrated consistent performance improvements, leading to thinner lamellas and smaller droplets compared to the original design in both simulations and experimental tests.
• The improved design highlights significant potential for energy consumption and operating cost reductions, as it outperformed the original nozzle even when operating at lower pressures and air-to-liquid ratios.
• Optimized ACLR nozzle design leads to 33 % smaller spray droplets (x90,3) compared to the initial (basic) design.
• has been elucidated in WP 2.

1. 1 Enhanced contact flexibility from nanoparticles in capillary suspensions

This work reveals how nanoparticles alter capillary suspension behaviors by reducing network heterogeneity and promoting liquid redistribution, as demonstrated by their structural responses under compression. Through confocal microscopy analysis coupled with rheological measurements, we demonstrate that nanoparticles create thin liquid films on microparticle surfaces and have a similar effect on wettability alteration, dramatically changing network dynamics. These films mitigate contactline pinning and facilitate liquid redistribution between bridges, resulting in narrower bridge size distributions and enabling easier particle rearrangement during compression. This investigation also indicates that nanoparticles positioned at microparticle contact regions diminish Hertzian contact, further promoting particle mobility. These combined effects result in capillary suspensions with enhanced contact flexibility, providing more controlled responses to external forces, which is a critical property for applications requiring precise deformation behaviors, particularly in industrial printing and additive manufacturing.

1. 2 Dewetting fingering Instability in capillary suspensions: role of particles and liquid bridges

This work examines the complex dewetting phenomena during the rapid stretching of suspensions, capillary suspensions, and capillary nanosuspensions using a modified Hele-Shaw cell with high-speed imaging. Microparticles are shown to enhance finger development through increased particle interactions and nucleation sites, while secondary liquid reduces fingering by creating stronger interparticle networks. Most significantly, the study demonstrates that nanoparticle addition induces earlier cavitation onset and enhances fingering instability while simultaneously reducing sampleto- sample variation. The investigation provides quantitative analysis of dendritic patterns and reveals that nanoparticles transform material failure behavior from adhesive to cohesive, promoting more even distribution between substrates during separation. These insights into high-speed stretching behaviors have substantial implications for printing processes and coating applications where controlled dewetting patterns directly impact product consistency and quality.

1. 3 Capillary forces-driven orientation in rod networks

Building on the surface modification effects observed with spherical nanoparticles, this Chapter explores how particle geometry provides an independent mechanism for controlling network properties. This Chapter introduces a novel approach to understanding anisotropic particle networks in capillary suspensions by analyzing single rod orientation, contact morphology, and resulting rheological behaviors. Via 3D particle detection algorithms, we demonstrate how secondary liquid drives a transition from point-to-point to side-to-side particle contacts, dramatically altering mechanical properties. Unlike spherical particle systems, these rod-based networks exhibit an inverse relationship between coordination number and clustering coefficient, indicating the formation of complex assemblies rather than simple side-to-side alignments. Through rheoconfocal measurements, the study captures chaotic cluster movements during yielding transitions, revealing localized mechanical responses invisible to bulk rheological measurements. The research provides a detailed analysis of particle contact types, orientation distributions, and network structural parameters, establishing a predictive framework for designing materials with orientationdependent properties through controlling rod alignment and bridge configurations.

1. 4 The mechanisms of yielding: How localized rearrangements drive global failure

This work reveals the mechanisms underlying particle network yielding through direct visualization of a capillary suspension model system using confocal microscopy. By adding small amounts of immiscible secondary liquid to create liquid bridges between particles, we establish a sample-spanning network where bond behavior can be observed directly. Our findings demonstrate that local rigidity deterministically predicts spatially heterogeneous yielding patterns. Visualization of bridge dynamics shows that bond stretching dominates a longer portion of the oscillation cycle compared to bridge retraction, despite the attractive nature of capillary forces. Through sequential analysis of physical processes, we identify distinct rheological fingerprints that demarcate three yielding regimes: an initial reversible region beyond the linear viscoelastic regime characterized by minor reorientations of flexible connections; an irreversible yielding zone in the flow direction marked by bridge stretching and retraction; and a catastrophic connectivity loss between clusters beyond the crossover point. These insights provide a framework for understanding yielding behavior not only in capillary suspensions but across particulate systems more broadly, with implications for industries spanning food production, pharmaceuticals, construction materials, and printed electronics.

1. 5 Identifying the precursor of structural failure in attractive gels

In this work, we focus on the yielding behavior of capillary suspensions, combining traditional rheometer and rheoconfocal setups with conventional rheological measurements and novel recovery rheology. Through recovery rheology combined with confocal microscopy, we optically confirmed particle displacement and its agreement with rheologically measured recoverable strains. We performed amplitude sweeps and captured the evolution of local particle configurations throughout the yielding process. Unlike Medium (Large) Amplitude Oscillatory Shear (MAOS/LAOS) analysis, which relies solely on Fourier transformation decomposition of stress response into waves of higher harmonics, our method directly links the development of stress derivatives in bulk with local yielding behavior, both rheologically and optically. This provides the foundation for developing a model that predicts failure patterns under different flow conditions. Additionally, we preliminarily examined the effects of nanoparticles, demonstrating how the contact-line pinning elimination results in lower recoverable strains. Optically, we observed that as interparticle movements become lubricated by nanoparticles, particle movement in the vorticity direction at small strains is also damped.

Executive Summary

The focus of this project is to understand the physical mechanisms that lead to defect formation – pitting, cracking, and delamination – during pharmaceutical tableting. A leading hypothesis among IFPRI members is that trapped interstitial air leads to high pore pressures that tend to fracture adhered particle interfaces after removal of the confining pressure. The project objective is to explore this problem through coupled numerical methods including:

• (i) continuum mixture models
• (ii) the discrete element method (DEM) coupled with a fluid solver.

The primary barrier to using these methods is that fact that the behavior of cohesive powders is not well understood, with neither a generally accepted constitutive relation nor contact model in existence.

To address this, the project has emphasized developing a reliable cohesive powder contact model for usage in DEM. This is the natural progression, since a powder DEM model will be indispensable in determining a constitutive relation for continuum simulations. In particular, we have concentrated on creating a mechanically-derived contact model for adhesive elastic-perfectly plastic particles.

In year one of the project, the majority of the theoretical framework for the contact model (i.e., the MDR contact model) was developed, but a number of issues remained. The JKR-type adhesion of the contact model needed to be validated once significant plastic deformation had occurred and the scheme to respect plastic incompressibility required an overhaul. The contact model was limited to simple symmetric loadings of a single particle, necessitating adaptation to many-particle interactions. Additionally, the model, initially coded in Matlab, needed implementation in an established software like LIGGGHTS or LAMMPS, with a reliable fluid-solid coupling strategy.

In year two, the theoretical framework was completed by validating the adhesive model within the fully-plastic regime and correcting the plastic incompressibility scheme. The completed contact model was published in the premier solid mechanics journal, Journal of Mechanics and Physics of Solids, as a two part series. Efforts to extend the contact model to the many-interacting particle case were started, as this was a necessary step to allow simulation of full-scale industrial applications. An initial implementation into LIGGGHTS was carried out and preliminary simulations showed promise in replicating compaction simulator data. Although progress was made, there were problems that remained both from a modeling and computational perspective when attempting to extend to the many-interacting particles case. On the modeling side, the rigid-flat placement scheme used to extend the MDR contact model formulation to the many-interacting particle case was realized to be inaccurate with increasing polydispersity. On the computational side, a switch from LIGGGHTS to LAMMPS was desirable for three primary reasons:

1. (i) LAMMPS is and will remain fully open-source with continual upkeep from Sandia National Laboratories (SNL),
2. (ii) Joel Clemmer and Dan Bolintineanu, two SNL research scientists and primary contributors to LAMMPS, volunteered to assist with the implementation of the MDR contact model into LAMMPS, and
3. (iii) LAMMPS provides the advantage of allowing immediate coupling with a multi-particle collision dynamics fluid solver, capable of simulating a compressible gas phase.

In the third year, a fully-parallelized implementation of the many-interacting MDR contact model was integrated into LAMMPS. The implementation was tested using both simple configurations involving a small number of particles and large-scale tableting simulations with tens of thousands of particles. This rigorous testing process prompted an overhaul of the rigid flat placement scheme and the development of a new topological algorithm to prevent contact through material during large deformation DEM. The unique ability of the MDR contact model to reconstruct deformed particle shapes was validated by comparisons with FEM predictions. The industrially relevant problem of pharmaceutical tableting was simulated, with experimental data provided by Vertex Pharmaceuticals for the compaction of Avicel PH102 (microcrystalline cellulose) serving as a benchmark. Good agreement was observed between experiments and numerical simulations for axial and radial stress measurements as functions of axial strain. Notably, the simulation also accurately predicted residual radial stresses after the release of axial confining pressure and the ejection force, aligning with experimental results. Preliminary coupled simulations involving the new DEM implementation and a compressible gas phase were also conducted. These simulations demonstrated that fracture caused by entrapped air could occur under specific loading conditions, though these were outside typical operating ranges.

In summary, a robust and reliable powder DEM model has been developed, which is open-source and accessible to all IFPRI members and is currently being used by some such as Amir Esteghamatian from Merck. Its utility in understanding defect formation in pharmaceutical tableting has been qualitatively demonstrated, and we are now positioned to conduct a comprehensive numerical investigation into air-induced defects. The mechanically-derived nature of the contact model offers two significant advantages:

• (i) it provides a solid foundation for the future development of a continuum constitutive relation, and
• (ii) it enables the simulation of a wide range of industrial powder compaction problems beyond tableting, provided the material properties are known.

The following report is split into four chapters. Chapter 1 gives a high level update of the project and details on progress made that is not included in the attached papers. Chapter 2 is the soon to be submitted to Powder Technology paper covering the major advances and results from extending the MDR contact model to the many-interacting particle case. Chapter 3 and 4 are both papers of the two part series published in the Journal of Mechanics and Physics of Solids. These papers contain detailed explanations regarding the theoretical background of the contact model in addition to validations made against finite element simulations.

The project aimed to develop a comprehensive set of models and decision tools for selecting and optimizing flow aids for the purpose of tackling the inherent challenges associated with the flowability of fine, cohesive powders. These powders often exhibit poor flow due to cohesion, which is influenced by factors such as particle size, shape, surface roughness, and environmental conditions. The project aimed to develop predictive models and decision tools that help select and optimize flow aids to improve powder processing. Over the past three years, significant progress has been made toward this goal, with several key accomplishments. Critical gaps have also been identified that will be addressed in the renewed project.

Major Accomplishments:

• Model guided dry coating (flow aid amount, size, and surface area coverage):
• Single and multi-asperity mechanistic contact models were surveyed and assessed for their ability to guide flow aid selection based on their effectiveness.
• A multi-asperity model, developed earlier in our group, was identified for its ability to explain how dry coated nano-flow aids work and result in improved powder flow as they lower the inter-particle cohesion by one to two orders of magnitude. This model, which uses a surface area coverage-based approach, accounts for factors such as the amount of silica, particles surface energy, particle surface roughness, and surface roughness distribution.
• Comprehensive validation of contact mechanics-based predictive models was conducted, focusing on selecting type and amount of silica for best flowability enhancements.
• An interactive mixture model provided a framework for assessing host-guest compatibility based on surface energy considerations.
• Material Characterization and Database:
• A database of industry-relevant materials was established to support informed decision-making for flow aid selection and suitability of dry coating.
• The functionality of different silicas (hydrophilic and hydrophobic) with varied sizes was examined to understand their impact on reducing cohesion in powders.
• Processibility Guidance:
• Ideal processing conditions using bench-marking dry coating devices like LabRAM were identified for the purpose of demonstrating that high-intensity mixing can significantly improve the use and efficacy of flow aids. This is expected to help explore the use of conventional mixing devices which will be further addressed in the renewal project.
• Synergistic effects in the flowability of blend were having a minor dry-coated component discovered, demonstrating improved blend flowability compared to that of its constituents.
• The effect of blend mixing time on this synergy when a dry-coated component is blended with other uncoated constituents was examined.
• Predictive Approaches:
• A dimensionless parameter, the granular Bond Number, based predictability of powder bulk properties was incorporated so that the same mechanistic model could be used for predicting the properties of uncoated as well as dry-coated powders.
• A size class-dependent Bond number approach was introduced to account for variations in cohesion for fine powders having broad and/or bimodal particle size distributions.
• Comprehensive approach for predicting flow aid, e.g., silica, performance in reducing cohesion was proposed by combining multiple models:
  1. Chen’s multi-asperity contact model: Explains the effect of host-guest sizes, guest surface energy, and host surface roughness on cohesion reduction.
  2. Deng’s stick and bounce model: Describes the aggregation tendency of nanoflow aids (e.g., silica) based on process intensity and guest-host particle sizes.
  3. Interactive mixture model: Based on host-guest total surface energy differential, predicts host-guest compatibility and coating efficacy.

These models provide a more nuanced understanding of how different flow aids, e.g., silica, perform under varying conditions, particularly concerning process intensity, nano flow aid particle size, and its surface energy.

• Industry Relevance:
• The findings underscore the importance of dry coating as a critical tool for enhancing powder flowability in industrial settings.
• Insights into powder blend design and processing have significant implications for improving end-product quality.
• A key highlight of this project is the successful evaluation and benchmarking of dry coating methods at both laboratory and pilot scales, achieved through collaborations with industry partners, including Merck, and support from NSF. Pilot-scale testing using scalable devices such as the COMIL-U10 validated the processability, scalability, and practicality of dry coating methods at pilot scale.

Industry liaisons provided important feedback and support during the project period including the quarterly project meetings. Consequently, several critical gaps have been identified that will be addressed in the renewal project.