Langley Research Center Turbulence Modeling Resource

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TURBULENCE MODEL NUMERICAL ANALYSIS

Grids - 2D Hemisphere Cylinder

The methodology to create a series of nested grids is provided. The coordinate system is defined with x streamwise, y horizontal, and z vertical. Each grid is a PLOT3D unformatted file of size ni x nj x nk. For the structured grids, the number of points in the spanwise direction (ni=2 for 2D), nj is the number of points along the body, and nk is the number of points in the normal direction. The grids range from 2 x 321 x 289 (finest grid) to 2 x 11 x 10 (coarsest grid). The constructed grids are not necessarily nested grids but coarser grids can be constructed by extracting every other point in two directions (i.e., regular refinement). (A capability to construct a nested family of structured grids with prolongation and restriction operators constructed using the grid mapping is available by preprocessing utilities within FUN3D.) The figure below shows a view of the 2D level 4 grid of size nj=41 x nk=37 in the streamwise x normal directions.

Note: be sure to use double precision when reading (or writing) the grids!

Note: be sure to use double precision when reading (or writing) the grids!

STRUCTURED VERSIONS OF GRIDS

PLOT3D Files

A simple FORTRAN program is provided that can be used to generate the grids in PLOT3D format. All information has been hardwired into the program except three integer inputs.

The first input is integer, between 1 and 6 indicating the level of the grid to be generated (finest to coarsest).

The second input is integer, between 0 and 2 and indicates the type of grid to be generated (0 is inviscid, 1 is laminar, and 2 is turbulent).

The third input is integer, between 1 and 3 and indicates the type of grid to be generated (1 is 2D, 2 is 3D with symmetry in y, 3 is 3D without symmetry in y). Use "1" to create a 2-D grid like that shown above; it is in the x-z plane with two planes in the y-direction.

Neutral Map Files associated with each grid are also generated by the above program (these files specify grid indices associated with each boundary condition - see The Neutral Map File). The following is an example neutral map file:

• Neutral Map File for (2-D) 2 x 41 x 37

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Last Updated: 05/13/2019