Tips & Tricks

CFD-FASTRAN/CFD-ACE+ coupling for thermal environment simulations

In certain applications, different regions of the computational domain experiences flow conditions that are so different that it is very difficult for a single solver to produce accurate results at the extremes. In many situations, such problems can be separated and solved using loosely coupled solvers. Each solver is chosen to provide highly accurate solutions for the prevailing flow conditions.

Cell Size Growth Control in CFD-VisCART

In CFD-VisCART, the Cartesian cells can split or grow by a minimum factor of 2 because of the intrinsic cartesian-cell-splitting algorithm. Due to this, in some cases, there is a chance that the mesh could grow from dense (at the wall) to coarse (away from the wall) within a short distance.

Wireframe Display in CFD-VisCART

Rotation, zoom, pan and other graphical operations require re-drawing of the model in the new position within the graphics window. When dealing with large models, these operations can slow down considerably due to the huge amount of graphical data that needs to be processed and re-drawn.

Avoiding Chimera Errors in CFD-FASTRAN

This note discusses a common error encountered by users when trying chimera meshes in CFD-FASTRAN. Such errors are easy to avoid and hopefully this note will assist you.

Motion Model Dependencies in CFD-FASTRAN

Moving-body models available in CFD-FASTRAN are highly suited to simulate complex prescribed and six-degree-of-freedom (6DOF) motions of rigid bodies. In many engineering problems, this translates to multiple bodies moving relative to one another.

Visual Display of Bad Cells in CFD-VisCART

Most models have certain parts or regions where the grid density needs to be higher than other areas to accommodate for steep curvatures, sharply changing topology, etc.

Using Local and Global Body Fit Factors in CFD-VisCART

The 'Body-fit Factor' is a percentage value used to determine how closely the Cartesian mesh front faces are projected to the real geometric surfaces. In other words, the Body-fit factor controls grid quality versus geometric fidelity. The value is between 0% and 100%, where 0%means no projection and 100% means complete projection to the surface.

Surface facet selection tool in CFD-VisCART

CFD-VisCART has always allowed surface selection where any surface can be selected by clicking on the graphics area or in the explorer window. Additionally, there is Facet Selection tool that allows the user to select individual facets or triangles of a surface (each surface is composed of triangulated faces called facets).

Low Mach Preconditioning and Dual Time Stepping in CFD-FASTRAN

Density-based schemes employing time-marching procedures available in CFD-FASTRAN provide excellent stability and convergence characteristics for high-speed compressible flows (typically M >0.5).

Axisymmetric 2D Convergent-Divergent Boattail Nozzle Simulation Using CFD-FASTRAN

The NASA D-1.22-L boattail nozzle configuration was obtained from the MADIC (Multidisciplinary and Design Industrial Consortium) program. The geometry definition and the flow conditions are documented in NASA TP 1766 [1]. This user tip presents a validation of numerical methods against experimental data.