Tips & Tricks

Geometric Precision and Filtering in CFD-GEOM

In many cases, CAD models can be dirty and thus do not import well into CFD-GEOM. Repairing these geometries can often take considerable time and effort. Many times, duplicate points, lines, and surfaces are created when importing CAD geometries.

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).

Plotting Multiple Variables in the CFD-VIEW Plotter

Plotting two or more variables on same plot having values of different magnitude/scale becomes difficult or many times impossible. In these cases plotting data with multiple Y-axes becomes very useful and sometimes necessary.

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.

Integer Cell Size Specification in CFD-VisCART

As it was explained in a previous tip called Understanding cell-splitting in CFD-VisCART and its effect on cell count, a small change in a specified cell size could lead to drastic changes in the cell count due to the cell-splitting rules used by CFD-VisCART.

Parametric studies using CFD-GEOM and SimManager

Parametric studies controlled by SimManager give the useful ability to perform several routine simulations. It allows to use CPU time more effectively and reduce user interaction. In other words, it is possible to automate the process of mesh generation in GEOM, model setup in CFD-AGE-GUI, solver run, and visualization in CFD-VIEW. In this user tip, automatic geometry manipulation and mesh creation will be discussed.

Importing external data in the CFD-VIEW Plotter

Comparing computational results to experimental data is a task often asked of CFD analysts and engineers. The line/curve plotter in CFD-VIEW is commonly used for plotting computational results along curves, such as line probes, surface slices, time histories, etc. CFD-VIEW offers a feature that allows users to import experimental or other external data in the same plot, thus making it easy to compare results.

Semi-Structured Domain Stitching in CFD-GEOM

A feature that allows users to stitch together a Semi-Structured domain is available in CFD-GEOM. This feature gives the user flexibility of stitching two end faces with different topologies, i.e. a geometry that cannot be extruded.