Computational Fluid Dynamics (CFD)


Veryst employs advanced computational fluid dynamics (CFD) tools and analytical models to understand and visualize complex flow behavior.  We use our grounded knowledge of computational methods, fluid mechanics, and physics to provide practical design recommendations.  Clients use our analyses to perform proof of concept investigations, understand product and process performance, and develop improvements, which has resulted in new intellectual property.  We stress the importance of engineering fundamentals as well as testing and validation for all of our modeling efforts, due to the complexity and nonlinear nature of many of the applications we encounter.

Our engineers’ experience includes using CFD tools to understand lipid nanoparticle self-assembly for mRNA vaccine production, biofluid dynamics problems, microscale flow and transport in microfluidic devices, flows of complex fluids like slurries or suspensions, and turbulent flows to predict mixing and heat transfer.  Our fluid flow analyses often involve other physics such as heat and species transport, chemical reactions and combustion, fluid-structure interaction, surface tension and wetting, and particle or cell motion. 

Streamlines over grooves in a microchannel.
Velocity magnitude of flow over grooves in a microchannel

Streamlines and velocity magnitude of flow over grooves in a microchannel.

Fluid Mechanics Expertise

We work extensively in solving fluid mechanics problems, including laminar and turbulent flows, single and multiphase systems, and interaction with other physics.

Mixing and Multicomponent Flows

A fundamental aspect of mixing is the stretching and folding of the interface between initially separated substances.  This occurs in many forms and systems: agitated versus static mixers, laminar versus turbulent flows, lab versus production scale, etc.  It also occurs in systems where mixing is weakly coupled with the flow (passive mixing) or tightly coupled with the flow (mixing of variable density substances, flows with chemical reactions, multiple phases, etc.).

The ring mixer enhances mixing via Dean flows – vortices in the channel cross-section generated by centripetal acceleration of fluid elements.
Microfluidic chaotic mixing



Microfluidics is the science and engineering of devices and processes involving flow through channels and chambers whose smallest dimension is less than 1 mm.  Examples include tools to model oxygen transport and uptake by cells within an organ-on-a-chip microfluidic device, chemical carryover and concentration gradients in a microchannel, chaotic microfluidic mixing, and lipid nanoparticle self-assembly for mRNA vaccine production.  Read more about microfluidics.

Shear stress on cells in a microchannel
Shear stress on cells in a microchannel


Capillary Flows, Surface Tension and Wetting

Veryst has considerable expertise in surface tension and wetting and capillary flow phenomena including wicking, bubbles (nucleation and mitigation), droplets (generation, adhesion, flow), cavitation, water repellency, patterned wetting, electrowetting, electrokinetic flows, contact angle hysteresis, and leakage/seepage through valves and seals.

Bubble motion in a microchannel
Bubble motion in a microchannel


Multiphase Flow

Multiphase systems include two or more materials (gas, liquid, or solid) flowing and interacting with each other simultaneously.  Examples of such systems include bubbles flowing through microchannels, the precipitation and self-assembly of lipid nanoparticles for mRNA vaccines, exhaled droplet plumes, sprays, nebulization, reagent dry-down and evaporation, and aqueous microdroplets transported in an immiscible oil carrier.  The interaction of the various phases can be complex and requires expert knowledge of the appropriate numerical techniques to capture that complex behavior in a simulation.

Computational fluid dynamics simulation of lipid nanoparticle self-assembly in a serpentine microfluidic mixer.
Lipid nanoparticle self-assembly in a serpentine mixer

Reacting Flows

Chemically reacting flows, like those found in bioreactors, engines, or fires, exhibit strong coupling between heat, mass, and momentum transport.  For applications involving turbulent flows, modeling the turbulence-chemistry interaction with appropriate fidelity is critical to obtaining useful insights into highly nonlinear processes.  For example, we’ve worked on the scale-up of bioreactors, thermal management of combustor liners, and flame propagation around obstacles within an enclosure.

Reactor scale up
Chemical reactor scale-up

Fluid-Structure Interaction

Fluid-structure interaction (FSI) refers to analyses involving coupled fluid flow and solid deformation.  Depending upon the problem, the interaction may be along a shared boundary or it may be internal to the structure, as in the case of poroelasticity.  In addition to the solid and fluid deformation, FSI requires handling a moving mesh.  Read more about fluid-structure interaction.

Micropump based on tilted flexible flaps
Micropump based on tilted flexible flaps

Thermal CFD and Conjugate Heat Transfer

Modeling of many thermal technologies requires coupling fluid-flow with heat transfer, often including conduction in the adjacent solids.  The coupled processes can be highly complex, particularly if the fluid flow includes turbulence or if the heat transfer involves processes such as radiation, boiling, evaporation, or mixed fluids with varying thermal properties.  Read more about thermal CFD.

Buoyant air circulation generated by LED lamp.
Buoyant air circulation generated by LED lamp

Complex Fluids and Rheology

Modeling processes involving complex fluids such as blood, particulate suspensions, and polymeric liquids requires sophisticated models and numerical techniques to capture their complex behavior.  Even in small-scale, non-inertial flows, such fluids exhibit a nonlinear stress response due to their micro-constitutive elements that impacts their dynamics and stability.  Example problems include blood flow and health, clogging of formulated products, granular abrasives, and binders in energy storage devices.

Flow of red blood cells in a capillary
Flow of red blood cells in a capillary

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Active Mixing in a Microwell by Repetitive Pipetting

A simple way of mixing small volumes (microliters or milliliters) of reagents is by repeatedly dispensing and withdrawing solution from a microwell or tube. In this case study, we used a two-phase multiphysics simulation with coupled fluid flow and mass transfer to analyze the efficacy of this active mixing process.

Chaotic Mixing in Microfluidic Devices

Fast mixing of reagents in microfluidic channels and devices is important for DNA sequencing, mRNA vaccine production in small-batch pharmaceutical processes, and point-of-care diagnostics. In this case study, Veryst used computational fluid dynamics simulations to evaluate the mixing performance of three commonly used microfluidic mixers.

Chemical Carryover in Microfluidic Devices

Removing reagents or sample from a previous processing step via a wash cycle is a common challenge in microfluidic assays used in diagnostic, genomic, biomedical, pharmaceutical and other applications. This case study shows how finite element simulations may be used to predict and optimize wash cycle performance.

Concentration Gradients in Microfluidic Devices

Controlling spatial variations in chemical concentration is important for designing and operating many microfluidic devices across a wide range of industries and applications including diagnostics, genomics, and pharmaceutics. In this case study, we show how simulations may be used to quantify and control concentration gradients in microfluidic devices.

Hemolysis in a Converging-Diverging Nozzle

Red bloods cells may be damaged in medical devices due to high shear stresses induced by their flow through the device. Veryst simulated turbulent flow of a converging-diverging nozzle specified in an FDA benchmark study, incorporating different hemolysis models to determine which areas of the device may damage red blood cells.

Laminar Static Mixer Analysis

Laminar static mixers are often employed in industrial environments when the mixing of two or more fluids is required. However, their performance is impossible to analyze with a pure CFD approach. Veryst, in collaboration with Nordson EFD, developed a unique computational modeling tool to evaluate and optimize the design of such mixers.

Micromixing in a Multi-Inlet Vortex Mixer

Flash nanoprecipitation (FNP) is a novel method to produce nanoparticles for a variety of applications, including mRNA vaccine manufacturing. This case study demonstrates the high-fidelity prediction of micromixing rates, which are critical to controlling the size distribution of nanoparticles created using FNP.

Oxygen Transport and Cellular Uptake in a Microchannel

Oxygen transport is a key factor in the design of cell culture systems such as organs-on-a-chip, microphysiological systems, and bioreactors. In this case study, we use multiphysics simulation to analyze oxygen transport and cellular uptake in a model microchannel bioreactor.

Simulation of Heat Transfer From Impinging Turbulent Jets

Arrays of impinging fluid jets are an effective design solution for applications requiring large heat transfer rates. This case study demonstrates the ability of computational fluid dynamics (CFD) to predict heat transfer coefficient distributions and guide design choices to improve cooling uniformity.

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