Kedar Chitale

Scalable Implicit Flow Solver for Realistic Wing Simulations with Flow Control

Massively parallel computation provides an enormous capacity to perform simulations on a timescale that can change the paradigm of how scientists, engineers, and other practitioners use simulations to address discovery and design. This work considers an active flow control application on a realistic and complex wing design that could be leveraged by a scalable, fully implicit, unstructured flow solver and access to high-performance computing resources. The article describes the active flow control application; then summarizes the main features in the implementation of a massively parallel turbulent flow solver, PHASTA; and finally demonstrates the methods strong scalability at extreme scale. Scaling studies performed with unstructured meshes of 11 and 92 billion elements on the Argonne Leadership Computing Facilitys Blue Gene/Q Mira machine with up to 786,432 cores and 3,145,728 MPI processes.

Parallel anisotropic mesh adaptation with boundary layers for automated viscous flow simulations

This paper presents a set of parallel procedures for anisotropic mesh adaptation accounting for mixed element types used in boundary layer meshes, i.e., the current procedures operate in parallel on distributed boundary layer meshes. The procedures accept anisotropic mesh metric field as an input for the desired mesh size field and apply local mesh modifications to adapt the mesh to match/satisfy the specified mesh size field. The procedures fully account for the parametric geometry of curved domains and maintain the semi-structured nature of the boundary layer elements. The effectiveness of the procedures is demonstrated on three viscous flow examples that include the ONERA M6 wing, a heat transfer manifold, and a scramjet engine.

Acoustic edge effect: Novel acoustophoretic cell retention to enable continuous bioprocessing

There is currently a shift in Bioprocessing towards continuous manufacturing of monoclonal antibodies or recombinant proteins in perfusion mammalian cell cultures (Konstantinov & Cooney, Journal of Pharmaceutical Sciences, 2015). A cell retention device is the key technology component that enables the shift to continuous production. A novel acoustic cell retention device operates by continuously drawing off a harvest flow, equal to the perfusion rate of the bioreactor, while recirculating the retained cells back to the bioreactor. The harvest flow path is tangent and significantly smaller than the recirculation rate. The device utilizes a novel acoustophoretic effect known as an “acoustic edge/interface” effect in conjunction with a recirculating flow beneath the acoustic harvest chamber which collects and returns cells to the bioreactor. This interface effect operates by creating a radiation pressure/force field at the interface between cell-free harvest and cell-laden circulating fluids. Numerical resul...

Macroscale angled ultrasonic standing waves: A novel approach for particle manipulation

Macro scale acoustophoretic devices use radiation forces to trap particles inside a standing wave to separate them from a mixture in a continuous fashion. However, these devices are limited by factors such as flow rates, residence times, and temperature rise which could be detrimental for certain applications. A novel method of separating, sorting and differentiating various particles using bulk angled ultrasonic standing waves is presented. This technique offers very sensitive separation capability with respect to size and acoustic contrast of particles. Universal curves are developed for particle deflection from the bulk flow direction at all wave angles as a function of a non-dimensional parameter defined by the ratio of acoustic radiation force to viscous drag force. Both CFD (Computational Fluid Dynamics) and model test data verify the analytical predictions. New macro-scale, ultrasonic separator concepts are presented that use the angle wave technology to effectively deflect and/or separate microcar...

A novel acoustic cell processing platform for cell concentration and washing

FloDesign Sonics has developed a technology to enable a single use (gamma irradiated) continuous cell concentration and wash application for manufacturing of cell-based therapies. The device has been designed to be able to process several liters of a suspended cell culture, e.g., T-cells, at concentrations of 1 to 10 M cells/ml. The cell suspension flows through the device and the acoustic radiation force field is used to trap and hold the cells in the acoustic field. After concentrating the cells, one or multiple washing steps are accomplished by flowing the washing fluid through the device, using the acoustic field to trap the cells while displacing the original cell culture fluid. The holdup volume of the device is about 30 ml. Results are shown for prototypes with a 1x0.75 inch flow chamber driven by 2 MHz PZT-8 transducers operating at flow rates of 1-2L/h, measured cell recoveries of 90% have been achieved with concentration factors of 20 to 50 for Jurkat T-cell suspensions, depending on cell concen...

Macro-scale cell manipulation using bulk ultrasonic standing waves for biopharmacy and cellular therapy applications

Acoustic standing wave fields are widely used in MEMS applications to manipulate micron sized particles in fluids with typical fluid channel dimensions of half a wavelength. This report presents three novel acoustofluidic platforms for particle separation and/or manipulation at macroscale, i.e., tens to hundreds of wavelengths. The first platform uses multidimensional standing waves which generate lateral radiation forces that trap and tightly cluster suspended fluid or particulate, enhancing the gravitational settling effect that results in continuous, macroscale separation. The second platform employs acoustic radiation forces generated near the edge of an acoustic standing wave to hold back particles and generate a wall type separation effect. The third platform uses the acoustic radiation forces generated by a macroscale, angled standing wave to deflect particles in a controlled fashion for particle manipulation and/or differentiation. Applications are focused in biopharmacy and cellular and gene ther...

Three-dimensional model for acoustic field created by a piezoelectric plate in a resonator

A three-dimensional model is developed to describe an acoustic field excited by a piezoelectric plate of finite size in a fluid filled resonator. First, the eigenfunctions (modes) of a bare plate are derived using general piezoelectric equations considering the elastic and electric properties of the plate. Then, the piezoelectric plate is placed into a fluid media such that only one plate side is in fluid and an acoustic field generated by the plate in the fluid is estimated. Finally, a reflector is placed to be parallel to the piezoelectric plate and acoustic field in a resonator is evaluated. The solution for a piezoelectric plate of finite size is obtained using Singular Value Decomposition (SVD) method. Equations for acoustic and electric variables are presented. Radiation force on spherical particles in the standing wave field is derived and discussed. Numerical results are presented to show the three-dimensional modal displacement and electrical characteristics of the plate at various frequencies an...