Tim Warburton

Graduate Student / Applied Math Division

tcew@cfm.brown.edu

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Nektar

These snapshots indicate some of the capabilities of the latest modules created for the general purpose Incompressible Navier-Stokes solver Nektar.

This is work continued under the supervision of Professor Karniadakis. This work is based on the original Nektar code of Spencer Sherwin. The code has been reworked in C++, and has been enhanced to allow triangles and now quadrilaterals in 2D, tetrahedra and now hexahedra, prisms and pyramids in 3D.

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The ALE-3D Module:

Flow past a fish flapping its tail. 1.1Mb mpeg movie four cycles from start up.

Smaller version of the same movie 42k mpeg movie

320k mpeg movie Almost periodic wake shedding (Play it continuously)... Many thanks to Maxia for helping with the visualisation.

Preview version of the same movie 12k mpeg movie

The ALE-2D Module:

Flow past a cylinder submerged under a free surface.

The NS-3D Module:

Flow in a branching pipe. This simulation was carried out at the Dept. of Aeronautical Engineering at Imperial College by Omar Shah under the supervision of Spencer Sherwin

Omar used the excellent mesh generation tool Felisa to generate this curved mesh. Felisa is an extremely versatile tool for generating tetrahedral meshes (as ever we are still looking for a polymorphic element mesh generator, we have big hopes for the GRUMMP package from Argonne National Labs).

The NS-F Module:

Flow past an airfoil that is periodic in the spanwise direction. (Simulation results courtesy of Spencer Sherwin).

The NS-HTF Module: (Heat Transfer Code)

Isocontours of temperature for flow past a spanwise periodic cylinder at Re=500. (Simulations run and visualised by Ma Xia).

The NS-2D Module:

Flow past a Naca airfoil at an angle to the stream velocity.

Flow past a cylinder. 250k mpeg movie

Flow past Spencer Sherwin's thumb.

Publications:

• T. Warburton, S. Sherwin and G. Karniadakis, Unstructured hp/spectral elements connectivity and optimal ordering. (CFM #95-8)
• T.C. Warburton, S.J. Sherwin and G.E. Karniadakis, Hierarchical refinement using spectral/hp triangles and prisms. (CFM #95-17)
• T.C. Warburton, S.J. Sherwin, and G.E. Karniadakis, Spectral Basis Functions for 2D Hybrid hp Elements. (CFM #97-4) (Submitted SIAM Journal of Scientific Computation)
• T.C. Warburton and G.E. Karniadakis, Spectral Simulations of Flow Past a Cylinder Close to a Free Surface. (CFM #97-7)

Acknowledgments:

Thanks go to the following people for results:

• Spencer Sherwin
• Ma Xia

Thanks go to the following for help with software:

• Fieldview from Intelligent Light.
• Henry Tufo for the use of his parallel communication package gs.
• George Karypis for the Metis domain decomposition package.
• Spencer Sherwin for the original version of Nektar
• NASA Langley for the mesh generation code Felisa
• J Peiro for assistance with spline surfaces and all things Felisa
• Omah Shah for Felisa filters

Where to contact me:

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