Generating inviscid and viscous fluid-flow simulations over an aircraft surface using a fluid-flow mesh

1. A computer-implemented method of generating a fluid-flow simulation over a computer-generated aircraft surface, the computer-generated aircraft surface comprised of a surface mesh of surface mesh polygons, the method comprising:

obtaining a fluid-flow mesh for simulating a fluid flow over the aircraft surface, the fluid-flow mesh comprising a plurality of fluid cells;

determining at least one inviscid fluid property for each of the fluid cells using an inviscid fluid simulation that does not simulate fluid viscous effects;

identifying a set of intersecting fluid cells of the plurality of fluid cells that intersects the aircraft surface;

identifying at least one surface mesh polygon of the surface mesh for at least one intersecting fluid cell of the set of intersecting fluid cells, wherein a number of the identified surface mesh polygons is fewer than a total number of surface mesh polygons that are intersected by the at least one intersecting fluid cell;

determining a boundary-layer prediction point for each identified surface mesh polygon;

determining at least one boundary-layer fluid property for each boundary-layer prediction point using the at least one inviscid fluid property of the corresponding intersecting fluid cell and a boundary-layer simulation that simulates fluid viscous effects; and

determining at least one updated fluid property for at least one fluid cell of the plurality of fluid cells using the at least one boundary-layer fluid property and the inviscid fluid simulation.

2. The computer-implemented method of claim 1 , wherein identifying the at least one surface mesh polygon for the at least one intersecting fluid cell comprises:

obtaining a centroid of the at least one intersecting fluid cell of the set of fluid cells;

identifying a surface mesh polygon having a centroid that is closest to the centroid of the at least one intersecting fluid cell.

3. The computer-implemented method of claim 2 , wherein the centroid of the at least one intersecting fluid cell is the centroid of a region of the at least one intersecting fluid cell that is outside of the aircraft surface.

4. The computer-implemented method of claim 1 , wherein the at least one boundary-layer fluid property includes a boundary-layer thickness value, the boundary-layer thickness value representing a distance from the aircraft surface where fluid viscous effects can be ignored.

5. The computer-implemented method of claim 1 , wherein the at least one boundary-layer fluid property includes a transpiration flux value, the transpiration flux value representing a direction and an amount of fluid flow originating from the aircraft surface.

6. The computer-implemented method of claim 1 , wherein the fluid-flow mesh is constructed using a Cartesian mesh, wherein the Cartesian mesh comprises:

a plurality of flow cells, each flow cell bounded by six flat faces where opposite faces are parallel and adjacent faces are orthogonal.

7. The computer-implemented method of claim 1 , wherein the inviscid fluid simulation is an Euler-based flow simulation.

8. The computer-implemented method of claim 1 , wherein the at least one inviscid fluid property includes a fluid velocity vector, a fluid density value, and a fluid pressure value.

9. The computer-implemented method of claim 1 , wherein the computer-generated aircraft surface is an airplane wing.

10. A computer-implemented method of generating a fluid-flow simulation over a computer-generated aircraft surface, the computer-generated aircraft surface comprised of a surface mesh of surface mesh polygons, the method comprising instructions for:

obtaining a fluid-flow mesh for simulating a fluid flow over the aircraft surface, the fluid-flow mesh comprising a plurality of fluid cells;

determining at least one inviscid fluid property for each of the fluid cells using an inviscid fluid simulation that does not simulate fluid viscous effects;

identifying an intersecting fluid cell of the plurality of fluid cells that intersects the aircraft surface;

determining a single boundary-layer prediction point for the intersecting fluid cell resulting in a one-to-one correlation between the intersecting fluid cell and the boundary-layer prediction point;

determining at least one boundary-layer fluid property for the boundary-layer prediction point using the at least one inviscid fluid property of the intersecting fluid cell; and

determining at least one updated flow property for at least one fluid cell of the plurality of fluid cells using the at least one boundary-layer fluid property and the inviscid fluid simulation.

11. A non-transitory computer-readable storage medium comprising computer-executable instructions for generating a fluid-flow simulation over a computer-generated aircraft surface, the computer-generated aircraft surface comprised of a surface mesh of surface mesh polygons, the instructions comprising instructions for:

obtaining a fluid-flow mesh for simulating a fluid flow over the aircraft surface, the fluid-flow mesh comprising a plurality of fluid cells;

determining at least one inviscid fluid property for each of the fluid cells using an inviscid fluid simulation that does not simulate fluid viscous effects;

identifying a set of intersecting fluid cells of the plurality of fluid cells that intersects the aircraft surface;

identifying at least one surface mesh polygon of the surface mesh for at least one intersecting fluid cell of the set of intersecting fluid cells, wherein a number of the identified surface mesh polygons is fewer than a total number of surface mesh polygons that are intersected by the at least one intersecting fluid cell;

determining a boundary-layer prediction point for each identified surface mesh polygon;

determining at least one boundary-layer fluid property for each boundary-layer prediction point using the at least one inviscid fluid property of the corresponding intersecting fluid cell and a boundary-layer simulation that simulates fluid viscous effects; and

determining at least one updated fluid property for at least one fluid cell of the plurality of fluid cells using the at least one boundary-layer fluid property and the inviscid fluid simulation.

12. The computer-readable storage medium of claim 11 , wherein instructions for identifying the at least one surface mesh polygon for the at least one intersecting fluid cell comprises instructions for:

obtaining a centroid of the at least one intersecting fluid cell of the set of fluid cells;

identifying a surface mesh polygon having a centroid that is closest to the centroid of the at least one intersecting fluid cell.

13. The computer-readable storage medium of claim 12 , wherein the centroid of the at least one intersecting fluid cell is the centroid of a region of the at least one intersecting fluid cell that is outside of the aircraft surface.

14. The computer-readable storage medium of claim 11 , wherein the at least one boundary-layer fluid property includes a boundary-layer thickness value, the boundary-layer thickness value representing a distance from the aircraft surface where fluid viscous effects can be ignored.

15. The computer-readable storage medium of claim 11 , wherein the at least one boundary-layer fluid property includes a transpiration flux value, the transpiration flux value representing a direction and an amount of fluid flow originating from the aircraft surface.

16. The computer-readable storage medium of claim 11 , wherein the fluid-flow mesh is constructed using a Cartesian mesh, wherein the Cartesian mesh comprises:

a plurality of fluid cells, each fluid cell bounded by six flat faces where opposite faces are parallel and adjacent faces are orthogonal.

17. The computer-readable storage medium of claim 11 , wherein the inviscid fluid simulation is an Euler-based flow simulation.

18. The computer-readable storage medium of claim 11 , wherein the at least one inviscid fluid property includes a fluid velocity vector, a fluid density value, and a fluid pressure value.

19. The computer-readable storage medium of claim 11 , wherein the computer-generated aircraft surface is an airplane wing.

20. A non-transitory computer-readable storage medium comprising computer-executable instructions for generating a fluid-flow simulation over a computer-generated aircraft surface, the computer-generated aircraft surface comprised of a surface mesh of surface mesh polygons, the instructions comprising instructions for:

obtaining a fluid-flow mesh for simulating a fluid flow over the aircraft surface, the fluid-flow mesh comprising a plurality of fluid cells;

determining at least one inviscid fluid property for each of the fluid cells using an inviscid fluid simulation that does not simulate fluid viscous effects;

identifying an intersecting fluid cell of the plurality of fluid cells that intersects the aircraft surface;

determining a single boundary-layer prediction point for the intersecting fluid cell resulting in a one-to-one correlation between the intersecting fluid cell and the boundary-layer prediction point;

determining at least one boundary-layer fluid property for each boundary-layer prediction point using the at least one inviscid fluid property of the corresponding intersecting fluid cell and a boundary-layer simulation that simulates fluid viscous effects; and

determining at least one updated fluid property for at least one fluid cell of the plurality of fluid cells using the at least one boundary-layer fluid property and the inviscid fluid simulation.