Bulletin of the American Physical Society
72nd Annual Meeting of the APS Division of Fluid Dynamics
Volume 64, Number 13
Saturday–Tuesday, November 23–26, 2019; Seattle, Washington
Session B16: Advances in CFD Algorithms I |
Hide Abstracts |
Chair: Rajeev Jaiman, UBC Room: 4c3 |
Saturday, November 23, 2019 4:40PM - 4:53PM |
B16.00001: Intersection-Based ALE for Radiation Hydrodynamics Patrick Payne, Marc Charest, HyeongKae Park Many of the existing methods for Lagrangian hydrodynamics utilize staggered-grid hydrodynamic (SGH) algorithms. However, the fact that the momentum is defined by a nodal- and cell-centered quantity makes it difficult to implementing exact, intersection-based remapping schemes that conserve momentum. Cell-centered hydrodynamics (CCH) eliminates these complications by storing all of the quantities at the cell-centers. By coupling a CCH method with a high-order, cell-centered radiation transport method provides a unique opportunity for modeling problems with complex and evolving geometries that contain high amounts of mesh deformation. By storing all quantities at the cell center, we can use an exact, intersection-based remapping algorithm and avoid complications introduced by nodal quantities. This algorithm avoids tangling and improves mesh quality. To the authors’ knowledge, these three elements are yet to be coupled in any existing framework. The work presented here details the implementation and challenges of coupling CCH, high-order radiation transport, and exact intersection-based remapping schemes. In addition, we present results from simulations of inertial confinement fusion using these elements and discuss the potential features that are made viable by the use of exact, intersection-based schemes, like mesh overlaying. [Preview Abstract] |
Saturday, November 23, 2019 4:53PM - 5:06PM |
B16.00002: Robust data assimilation using mixed-norm optimization Souvik Ghosh, Vincent Mons, Olivier Marquet, Denis Sipp, Peter Schmid Experimental data are often contaminated with outliers which in turn influence the quality of recovery in data assimilation techniques. We develop and present a computational framework based on mixed-norm optimization to determine flow fields from experimental measurements via a data-assimilation technique. More specifically, we use a variational adjoint-based methodology to balance a recovery error with a sparsity constraint, resulting in a saddle-point problem. The method shows promise in situations where only sparse measurements are available. Applications from mean-flow recovery at lower Reynolds numbers, as well as Reynolds-stress recovery at higher Reynolds numbers, will be presented. [Preview Abstract] |
Saturday, November 23, 2019 5:06PM - 5:19PM |
B16.00003: A Novel Numerical Solver for Incompressible Two-Fluid Flows at High Reynolds Numbers Zixuan Yang, Shizhao Wang, Guowei He We present a proposed novel numerical method for robust simulations of two-fluid flows at high Reynolds numbers. The conservative form of the momentum equation is solved, and the convection equation of density is evolved together with the momentum equation at all cell faces. Consistent schemes are used to calculate the density and momentum fluxes. The interface between the two fluid phases is captured using the coupled level-set and volume-of-fluid method. The interface is kept sharp without any diffusion of the density or viscosity around the interface. The performance of the new algorithm is tested using two canonical cases: the convection of a high-density droplet and the collapse of a 2D water column. The results of the proposed method are in excellent agreement with analytical solutions and the results of laboratory experiments. The proposed method is also used to simulation two 3D cases with complex interface geometries: a plunging wave at a high Reynolds number and a collapsing water column impinging onto a fixed object. The test results show that if the interface is kept sharp and if the mass of each fluid phase is effectively conserved, the dynamics of the interface can be predicted accurately at a relatively low grid resolution. [Preview Abstract] |
Saturday, November 23, 2019 5:19PM - 5:32PM |
B16.00004: A Finite-Difference Scheme for Three-Dimensional Incompressible Flows in Spherical Coordinates Luca Santelli, Paolo Orlandi, Roberto Verzicco In geophysics and astronomy, solving the Navier-Stokes equations in spherical coordinates is a desirable option owing to the simmetry properties of boundaries and discretization. Unfortunately, these equations have two singularities, at the centre and along the polar axis, that make their integration exceedingly difficult. In this paper, a second-order finite-difference scheme for 3D, incompressible flows in spherical coordinates is presented. Thanks to a staggered mesh and a change of variables, the singular boundaries become trivial boundary conditions for the modified variables. The integration is performed by a fractional-step method with implicit viscous- and explicit nonlinear-terms. The elliptic equation for incompressibility benefits from a direct solver thus obtaining a free divergence velocity field within round-off error. The algorithm is efficient and flexible allowing any mesh distribution in two of the three spatial directions. The method has been validated by a Hill vortex crossing the singular boundaries and comparing the results with simulations in Cartesian coordinates and the theory. The scheme has been used also for Rayleigh-BĂ©nard convection within spherical shells and the results compared with the literature. [Preview Abstract] |
Saturday, November 23, 2019 5:32PM - 5:45PM |
B16.00005: Hydrodynamic Simulation of Counterstreaming Plasmas with a Multifluid Model Debojyoti Ghosh, Richard Berger, Thomas Chapman, Andris Dimits, Jeffrey Banks The dynamics of counterstreaming plasmas is important in many applications such as astrophysical flows and high energy-density physics (HEDP) foil experiments. Conventional hydrodynamic codes, including multispecies codes, fail to capture this phenomenon due to a single velocity field representing all plasma species or streams. In this talk, we present a multifluid model that solves a distinct set of Euler equations for each fluid, thus representing each plasma stream with its own velocity field. Inter-fluid interactions comprise electrostatic forces, friction, and thermal equilibration. An inertialess electron model is used to avoid the numerical difficulties of resolving electron dynamics. The governing equations are discretized in space using the conservative finite-difference formulation and the 5th order MPWENO scheme. High-order, conservative, multi-stage implicit-explicit time integrators are used to evolve the solution in time, where the convective and acoustic time scales are integrated explicitly, while the temporally-stiff friction and thermal equilibration terms are integrated implicitly. We present plasma interpenetration simulations that are representative of HEDP foil experiments. [Preview Abstract] |
Saturday, November 23, 2019 5:45PM - 5:58PM |
B16.00006: ABSTRACT WITHDRAWN |
Saturday, November 23, 2019 5:58PM - 6:11PM |
B16.00007: Symmetry preservation in WENO schemes Ersin Ozbenli, Prakash Vedula Weighted essentially non-oscillatory (WENO) schemes are commonly used in numerical solution of hyperbolic PDEs and are especially known for their remarkable performance in simulation of problems containing strong discontinuities. Similar to most numerical schemes in CFD, WENO schemes are also usually constructed such that the primary focus is on the accuracy of the solution but not on Lie symmetry groups associated with PDEs underlying these schemes. We showed in our earlier works (e.g. \emph{Ozbenli and Vedula, Journal of Computational Physics}, 349, 2017) how consideration of Lie groups in commonly used numerical schemes could potentially lead to significant improvements in the accuracy of numerical schemes, especially when error measures based on Lie symmetries are considered. In this study, we extend earlier works, based on equivariant moving frames, on Lie symmetry preservation in numerical schemes and present construction, analysis and application of invariant (or symmetry preserving) WENO schemes. Performance of the proposed invariant WENO schemes is evaluated via implementation to inviscid Burgers' equation and Euler equations. Preliminary results indicate that our proposed invariant WENO schemes generally perform better than their non-invariant counterparts. [Preview Abstract] |
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