Tips & Tricks

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.

Digital Signal Processing using CFD-VIEW

Signals (stream of data) obtained from physical or numerical experiments often require additional processing to understand/interpret the physics they represent. The processing of signals through digital means is termed Digital Signal Processing (DSP).

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.

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.

Chemical-kinetic Model for Mars Atmosphere Re-entry Applications

The shock layer flow over a blunt body entering a planetary atmosphere at a hypersonic speed will dissociate and partially ionize. A reliable prediction of the flow-field for such application requires a chemical-kinetic model. For Mars atmosphere, the five species Park'94 is considered [1]. The dissociation of CO2 is producing C, CO, CO2, O and O2.

User Defined Curve Probes in CFD-VIEW

CFD-VIEW allows the user to create curve probes from a file containing XYZ data. This feature gives the user flexibility of collecting data on any specified/desired curve in the computational domain. As an example of use, these "curved line" probes could be used to sample simulation data at the same locations that experimental data was collected.

Tracking Multiple Variables with Multiple Legends

When post-processing with CFD-VIEW, one may wish to display two different variables on two different objects. This requires the use of two legends to correspond to the different color mapping of the variables. The legend tracking feature in CFD-VIEW can be used to achieve this. If this topic is of interest to you, please read on.

Improvements to Parallel Simulation Setup in CFD-FASTRAN

Setting up and launching a parallel simulation has become much simpler and easier in FASTRAN. This note discusses some of these developments. Let’s start with things that have not changed. There are still two versions of CFD-FASTRAN solvers for parallel cases. The difference between the two versions is the underlying parallel communication mechanism, the choice of which is decided by the type of mesh used.