Original Grid and Geometry:

Below is the volume grid that was obtained by using the 3DMAGGS code for volumetric discretization and the Langley Aerothermodynamic Upwid Relaxation Algorithm (LAURA) code. The problem posed was to perform multiple zonal adaption where each zone is separated by some flow feature that may occur across multiple grid blocks. Shown in the figure below is the domain of the flow adapted using the LAURA software. Note that only the entropy gradient furthest from the wall is captured.

Multiple Block Grid

Preparing for Grid Adaption:

Utilizing the Parametric Remapping technique of the VGM software, the multiple zonal grid adaption can be done. Set up of the technique requires a coarse adaption of the grid based on a selected flow variable or a multiple set of flow variables. Since both types are similar, the multiple set is identified here. The process of determining how to adapt a grid line begins by identifying the control points along the line where clustering is to be created. These control points are usually locations where a flow variable has an inflection from maximum to minimum and vice versa. Since the VGM language supports various methods for using the control points, two are discussed but only the final result is shown. For the flow field at hand, entropy, density,

Entropy and Density in Flow Domain

and the magnitude of velocity

Grid and Density in Flow Domain

contour profiles are used to identify the control points. Looking along the K-direction for a single line in the wake of the flow domain, the control points are easil identified by the plot of the variables.

Adaptation Control Points

Use of these control points can be used to redistribute the available grid points along the line, one adaption for each flow variable or one adaption for all three variables. If one adation for each flow variable is used, the distribution function for the grid line can be combined by taking one third of each normalized adapted grid line and summing them to form one distribution function. In either case, a grid line is adapted to capture the flow variable gradients.

An Adapted Grid Line

This adaption is performed on a significantly reduced subset of the volume grid, to obtain a coarse adapted grid.

Grid Lines to Control Adaptation

Using the coarse grid as a basis for the remaining adpation of the volume grid, Parametric Remapping is used to recompute the distribution function between the adapted grid lines for the non-adapted grid lines. The new volumetric distribution functions in the K-direction are then used to perform the final grid adaption which is shown below, or a complete ( full grid point density).

Coarse Isotropically Adapted Grid

NASA Official Responsible for Content -- Stephen J. Alter Last Updated November 6, 2002
Feedback on Langley Products and Services