TAFSM

Team for Advanced Flow Simulation and Modeling



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For more information:
  tezduyar@gmail.com

Dynamics of a Paratrooper Jumping from a Cargo Plane

In this example we are studying the dynamics of a paratrooper jumping from a cargo aircraft which is traveling at 130 Knots. We use the space-time finite element formulation in combination with our mesh moving algorithms to numerically simulate this fluid-body interaction problem on a CRAY T3D.

A finite element mesh has been created for the cargo plane and paratrooper combination using our automatic mesh generation software. This mesh contains approximately 880,000 tetrahedral elements for half of the domain (since the geometry is symmetric). Since the flow conditions are at very high Reynolds numbers, a Smagorinsky turbulence model is used. We use the automatic mesh moving scheme in combination with remeshing to move the mesh in response to the motion of the paratrooper. The paratrooper is allowed to translate and rotate freely governed by Newtons laws of motion.

The initial condition for this time-dependent simulation is the steady-state flow past the cargo plane with the paratrooper located within the open side door of the plane (a portion of the interior of the plane is also modeled). The top image below shows the steady-state pressure distribution on the surface of the plane, the center the pressure distribution on the paratrooper at one time instant with streamlines, and the bottom the position and orientation of the paratrooper at different instants during the simulation. The paratrooper motion is initialized with a small outward velocity. This simulation was used to validate the numerical tools for use in such applications.

The unstructured mesh generator, flow solver, and flow visualization software (based on Ensight, and Wavefront) were developed by T*AFSM.

References:

1. T.E. Tezduyar, "Stabilized Finite Element Formulations for Incompressible Flow Computations", Advances in Applied Mechanics, 28 (1991) 1-44.

2. T.E. Tezduyar, M. Behr and J. Liou, "A New Strategy for Finite Element Computations Involving Moving Boundaries and Interfaces--The DSD/ST Procedure: I. The Concept and the Preliminary Numerical Tests", Computer Methods in Applied Mechanics and Engineering, 94 (1992) 339-351.

3. T.E. Tezduyar, M. Behr, S. Mittal and J. Liou, "A New Strategy for Finite Element Computations Involving Moving Boundaries and Interfaces--The DSD/ST Procedure: II. Computation of Free-surface Flows, Two-liquid Flows, and Flows with Drifting Cylinders", Computer Methods in Applied Mechanics and Engineering, 94 (1992) 353-371.

4. S. Mittal and T.E. Tezduyar, "Massively Parallel Finite Element Computation of Incompressible Flows Involving Fluid-Body Interactions", Computer Methods in Applied Mechanics and Engineering, 112 (1994) 253-282.

5. A.A. Johnson and T.E. Tezduyar, "Mesh Update Strategies in Parallel Finite Element Computations of Flow Problems with Moving Boundaries and Interfaces", Computer Methods in Applied Mechanics and Engineering, 119 (1994) 73-94.

6. T. Tezduyar, "Advanced Flow Simulation and Modeling", Flow Simulation with the Finite Element Method (in Japanese), Springer-Verlag, Tokyo, Japan (1998).

7. T. Tezduyar, "CFD Methods for Three-Dimensional Computation of Complex Flow Problems", Journal of Wind Engineering and Industrial Aerodynamics, 81 (1999) 97-116.

8. T. Tezduyar and Y. Osawa, "Methods for Parallel Computation of Complex Flow Problems", Parallel Computing, 25 (1999) 2039-2066.