In the pharmaceutical industry, special types of processing equipment are designed to blend, mix, dry, compact, and coat the various materials that go into making the pills, tablets, powders and other products that are produced. To ensure the safety, quality, and consistency levels critical for the target outputs, these equipments are often subject to various scale-up and validation experimental tests, which can be quite expensive to execute in terms of both time and materials.
Increasingly, engineers and researchers who design and optimize pharmaceutical processing equipment are turning to discrete element modeling (DEM) software during their research and development phases. They use the simulation software, often in tandem or even in place of laboratory tests, to analyze and improve their equipment faster and with less overall expense than their real-world testing. The key to success in this space, however, is the accuracy of the DEM simulation results and the speed with which those results can be obtained and analyzed.
Some key reasons why researchers and engineers choose particle simulation software to analyze their pharmaceutical equipment are explored below.
Accurate Product Shape Representation
The unique shape of a product can have a big effect on how it is processed. Therefore, being able to model accurate, polyhedral convex and concave particle shapes is a feature that can set some particle simulation tools apart from the competition.
When compared to the glued sphere representations used by many standard DEM codes (Figure 1), more advanced DEM codes using polyhedral shapes not only appear closer to reality with the sharp edges and corners not possible with sphere clumps, but they also produce more realistic void fractions, settling behavior, and friction results—all of which have an effect upon the accuracy of the simulation results.
Figure 1: Glued sphere shape used in standard DEM software (left); Polyhedral shape used in Rocky DEM (right)
And because each polyhedral-shaped particle is calculated as a single meshed shape, it takes fewer resources to process than many individual spheres glued together, so the simulation time is often much shorter for the same amount of particles.
Advanced Prediction of Product Breakage
When processing pharmaceuticals, product breakage is not usually a desirable outcome. Predicting when breakage is likely to occur during processing is therefore an important way that engineers can design and optimize equipments to avoid it. Using a breakage model along with an accurate polyhedral shape representation of the product can help engineers analyze phenomena like pill and tablet product breakage (Video A), and ultimately design ways to mediate it.
Video A: Rocky DEM simulation of a particle breakage.
Faster Processing on Multi-GPU Solvers
Due to the relatively small powder sizes used in the pharmaceutical industry, processing power is a particular challenge that in the past has limited the practical use of particle simulation. It was nearly impossible to achieve the multi-million particle amounts required in a timeframe reasonable enough to act upon.
Several DEM tools have improved the simulation processing time many times over by allowing processing to be shared between the CPU and a single Graphics Processing Unit (GPU) card, but it turns out that the real gains are seen when the technology enables processing on not just one, but multiple GPUs. Sharing the processing across the combined memory of two, three, or more GPU cards on the same motherboard means that researchers are for the first time able to closely match the high particle amounts used in laboratory tests, with tens of millions of individual particles now feasible (Video B).
Video B: Rocky DEM Multi-GPU simulation of a 150L Commercial Scale High-Shear Granulator with ~10 million particles
Complex Mixing and Blending Motions, and Heat Transfer
Being able to set up your mixing (Video C) and blending (Video D) motions—even complicated multi-directional ones involving drying or heat transfer (Video E)—directly within your software is another benefit some particle simulation tools offer. Not having to use third-party motion tools can save time and produce more accurate results.
Video C: Ring-pan mixer using combined motions simulated in Rocky DEM
Video D: V-Blender mixing comparison simulated in Rocky DEM
Video E: Conical Double-Screw Dryer simulated with thermal properties in Rocky DEM
DEM-CFD coupling for simulating fluids, integrated post-processing tools, and more: there are many reasons why engineers and researchers are using particle simulation software to help improve their pharmaceutical processing equipment. To learn more on this subject, read the book Predictive Modeling of Pharmaceutical Unit Operations.