Towards Virtual Finite Volume, Meshless, Dynamically Programmable and Problem-adaptive CFD With applications in combustion and multi-physics framework

Dr. Aki Runchal, ACRi-Analytic &
Computational Research, Inc.

For users of CFD codes today, generating a high quality grid is often the most expensive and painful part of the simulation. It is not uncommon for a complex practical problem to require weeks of grid generation effort while the CFD solution can be obtained in matters of days, if not hours. In addition, the CFD software of today is typically designed with a limited world view of its range of applications and capability. For example take a simple requirement that the boundary conditions at an inlet may be an arbitrary function of time, space and, say, pressure just downstream of the boundary. Most CFD codes of today require that the user write code ("User Function") to implement this option.

Consider now the case where one may need to account for phenomena that depend on special processes that require solution of additional phase space equations that involve complex interaction of phase space variables. What happens, for example, if a nuclide transport code requires the solution of 50 additional equations due to complex chain reactions? What about the processes that may become very important in an extremely low gravity environment of the outer space? Such applications typically require that the user write special code to extend the capability of the CFD code.

Generating grids and writing code (in C or FORTRAN) is expensive and time consuming. Ensuring that the coding is correct is an elaborate and expensive process - and a QA headache.

This talk outlines the Virtual Finite Volume (VFV) concept implemented by the author and his colleagues at ACRI that considerably eases the pain of grid generation. Additionally it describes the steps taken to write dynamically programmable and problem-adaptive CFD software. Such practices make it easier to implement arbitrary multi-physics mathematical framework with simple English-language macros rather than writing FORTRAN or C code. The CFD software can accommodate practically any phase space, initial or boundary conditions and physical processes that fit within the general framework of 2nd order convective-diffusive transport equations. These ideas have been applied to a wide range of aerospace and environmental applications. The author will describe some of these applications.

The P/T Colloquium is
typically held each
Thursday, 3:45–5:00 PM.

Collaborations and Refreshments, 3:15 PM.