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Research - Low-Speed Flows


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Low-Speed Flows

Low speed flows are characterized by a large or infinite sound speed, relative to the fluid velocities in the system (i.e., small Mach number). Most of the physical systems of common interest are of this type. The challenge in these types of flow is that changes locally can influence all other aspects of the flow almost instantaneously. Techniques for treating these flows have been in development since the early days of T-3.
This is a new reactive flow algorithm under development in T-3 for simulating a variety of hydrodynamic phenomena ranging from low-speed incompressible flows to shock-wave hydrodynamics. In-cylinder combustion of gasoline and diesel engines, external vehicle aerodynamics, underhood cooling, vehicle air conditioning, and high-velocity impact simulations are some of the applications where this algorithm may be usefully employed. This is the first three-dimensional T-3 algorithm to have a fully implicit and coupled solution to the Navier-Stokes equations, thereby eliminating the traditional separation of the Lagrangian and rezone phases. The flow solver employs an implicit finite-volume technique that performs surface integrals in parallel loops over connections associated with the two terminus nodes [Mavriplis, 1995]. A continuous transition between explicit and implicit advection is employed that is second-order accurate for Courant numbers less than unity and is monotone and unconditionally stable (a 3D extension of the scheme of Collins, et al. [Collins et al, 1995]). Other unique features of the algorithm are an accurate treatment of the diffusion terms and an accurate gradient limiter for an arbitrary number of nearest neighbors associated with a node.

Los Alamos Lowspeed Flows Projects
All of the filled circles are linkable projects.
All of the empty circles are navigational guides.

  • Low gravity flows
  • Modeling Surface Tension
  • All speed numerics

This is from "The Legacy and Future of CFD at Los Alamos" (LAUR#LA-UR-1426)(365Kb pdf file)






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