Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session P20: Computational Fluid Dynamics |
Hide Abstracts |
Sponsoring Units: DFD Chair: Anand Oza, New Jersey Inst of Tech Room: 301 |
Wednesday, March 4, 2020 2:30PM - 2:42PM |
P20.00001: Multicanonical Studies of Fluid Behavior David Yevick, Ming Tong We applied the multicanonical procedure to the nonlinear Schrodinger equation in order to generate the probability distribution function (pdf) of rogue wave heights in the region of extremely small probabilities. This yielded a simple parametrization of the dependence of the slope of the pdf on the nonlinearity coefficient for large amplitudes. [M. Tong and D. Yevick, Wave Motion 66, 56 (2016) We subsequently investigated the pdf of the drag generated by of a rectangular obstacle associated with random changes to either the input flow pattern or the boundary profile. Our results demonstrated that by integrating the multicanonical and lattice Boltzmann procedures, the probability of highly unlikely drag values can be determined with high accuracy. [M. Tong and D. Yevick, Physics of Fluids 30, 033605 (2018) |
Wednesday, March 4, 2020 2:42PM - 2:54PM |
P20.00002: Rotating Cylinder as a Flow Split Controller in a Rectangular T-channel: Power-Law Fluids Anamika Maurya, Naveen Tiwari, R.P. Chhabra The present work endeavours to understand numerically the flow characteristics of power-law fluids in a rectangular T-channel over a wide range of conditions: power-law index (0.2 ≤ n ≤ 1), the rotational velocity of the cylinder (-5 ≤ α ≤ 5) at Re = 45. A rotating cylinder (both in the clockwise (α > 0) and anticlockwise (α < 0)) placed at the T-junctions is used here as a flow rate controlling strategy from the channel outlets. The flow is assumed to be steady, laminar and incompressible. The detailed flow kinematics has been visualized in terms of streamline patterns, flow-split ratio (i.e., the ratio of the main branch flow rate to the side branch flow rate), hydrodynamic forces (total and its pressure component) over the cylinder surface and torque (due to the force required to maintain the cylinder rotation in the free stream of power-law fluid). The flow split ratio is seen to be significantly affected by the cylinder rotation while the stationary cylinder is found to divide the flow equally in both main and side branches. The total hydrodynamic force and its pressure coefficient are seen to be a strong function of cylinder rotation as well as the power-law index. The magnitude of the torque is seen to be independent of the direction of cylinder rotation. |
Wednesday, March 4, 2020 2:54PM - 3:06PM |
P20.00003: Scale resolving simulations of flow past a heated sphere using non-linear eddy viscosity closure SAGAR SAROHA, Krishnendu Chakraborty, Sawan Sinha, Sunil Lakshmipathy The partially-averaged Navier-Stokes (PANS) method of turbulence computations has been employed in recent years to perform scale-resolving simulations of various canonical as well flows of practical interest. While in most flows PANS shows improvements over the Reynolds-averaged Navier-Stokes (RANS) method, further scope of improvement still exists, especially in massively separated flows, wherein the linear eddy viscosity assumption is suspected to misrepresent some essential flow physics. With the motivation to address this shortcoming, we augment the PANS methodology using a non-linear (quadratic) constitutive equation. We examine the performance of this enhanced PANS methodology in flow past a heated sphere at Reynolds number of 10000. We find that the non-linear PANS methodology shows improvements over it conventional counterpart (PANS using linear eddy viscosity assumption) in terms of several hydrodynamic (drag and pressure profiles over the sphere surface, axial and transverse velocity profiles and wake structures), as well as some temperature-related flow features (mean temperature profiles around the sphere and Nusselt number). In this talk these results along with some pertinent explanations and insights will be presented. |
Wednesday, March 4, 2020 3:06PM - 3:18PM |
P20.00004: Lattice Boltzmann Simulations of Magnetohydrodynamic Flows on a Rectangular Grid using a Central Moments Formulation Eman Yahia, Kannan Premnath Simulations of magnetohydrodynamic (MHD) flows, especially in wall-bounded flows involving the resolution of Hartmann layers, are particularly effective with numerical techniques based on stretched grids. Lattice Boltzmann methods (LBMs) are highly parallelizable local algorithms based on collide-and-stream steps. Here, we extend a prior LBM formulation for MHD, which was constructed for square grids, to handle rectangular lattice grids. Our approach is based on augmenting the equilibria of a vector distribution function with terms involving the grid aspect ratio obtained via a Chapman-Enskog analysis in such a way that it consistently solves the magnetic induction equation. Similarly, the equilibria of another scalar distribution function representing the electrically conducting fluid motion subjected to the Lorentz force are extended with corrections terms based on the aspect ratio so that it correctly recovers its isotropy. For robust simulations, the collision steps of both the scalar and vector distribution functions are based on the relaxation of their central moments to the corresponding equilibria. Computations of various MHD flows at different Hartmann and magnetic Prandtl numbers based on our novel LB formulation demonstrates its accuracy and effectiveness. |
Wednesday, March 4, 2020 3:18PM - 3:30PM |
P20.00005: Data-driven A priori analysis of sub-grid scale stress closures Aviral Prakash, Kenneth Jansen, John A Evans Better affordability of computational resources over the past decade has led to |
Wednesday, March 4, 2020 3:30PM - 3:42PM |
P20.00006: Adaptive time-step selection in volume of fluid (VOF) simulations Ashkan Davanlou In numerical simulations, Volume of Fluid (VOF) approach is a well-established method in capturing the interface and solving multiphase problems. However, choosing the appropriate time step can be a challenging task for majority of users both with commercial software as well as in house codes. Therefore, we implemented a CFL based time-step control that can target a given area such as the cells intersecting the free surface, such that the CFL limit can be imposed where it is needed. In addition, we keep the sub-steps constant. This enhancement is useful in casting, tank sloshing and marine applications. |
Wednesday, March 4, 2020 3:42PM - 3:54PM |
P20.00007: Control of Unstart Phenomenon in a Hydrogen Fuelled Scramjet model ANCHAL VARSHNEY, Mehul Varshney, MF Baig The present work involves the development of a numerical methodology to model supersonic combustion using 8 species, 13-reaction chemical model. The governing equations of continuity, momentum, energy, and combustion(species conservation) have been solved using commercial code of Fluent. The methodology has been then used to model the unstart phenomenon in a scramjet engine. A control system based on the mitigation of unstart by leaking high-pressure fluid from the slots designed on the lower and sidewall of the scramjet has been studied[1]. The effect of the slot size position on control mechanism has been studied. The unstart is initiated by a) raising a solid flap downstream of the isolator b) heat release due to combustion of fuel. An automatic slot control mechanism has been suggested to control the unstart phenomenon. The effect of bleeding ratio through slots on engine performance parameters has also been explored. |
Wednesday, March 4, 2020 3:54PM - 4:06PM |
P20.00008: Experimental & CFD Analysis, Design & Optimisation of the Cooling System of a Formula Student Racecar Ayush Mittal, ANCHAL VARSHNEY, Mehul Varshney FSAE cars witness a persistent problem of Engine overheating because of inefficient cooling system used. Paper emphasises on complete |
Wednesday, March 4, 2020 4:06PM - 4:18PM |
P20.00009: Flow dynamics in an aneurysm: Effect of prolonged exercise Mehul Varshney, Abdullah Y. Usmani Present work involves the study of non-invasive treatment of unruptured Abdominal Aortic Aneurysm subjecting the patient to certain physiological level of heart. This technique was initially studied by Varshney et al. [1] Flow topology for 3-D axisymmetric and asymmetric aneurysm is studied under resting (Re=200), mild exercise (Re = 750) & moderate exercise (Re=1200) conditions. Pulsatile flow is given at inlet. Hemodynamic indicators are quantified in terms of time-averaged wall shear stress, oscillatory shear index. The trajectories of vortex-core movement (using Q-criterion) are correlated to pressure peaks attained at the wall. For symmetric aneurysm, it was seen that the resting condition manifests the aneurysmal wall to recirculating fluid for most of the cycle time. Moderate and high exercise exposes the aneurysmal wall and the distal end to high pressure, which otherwise has low intensity under mild activity Thus, mild exercise for a prolonged duration is effective in non-invasive symmetrical aneurysmal treatment. Similar study will be done for an asymmetric aneurysm. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700