For situations where the analyst or engineer is not able to define through measurements or experience the general flow scheme, RadTherm analyses can be combined with a CFD code to provide a full three-dimensional flow analysis integrated with RadTherm's three-dimensional radiation and conduction. CFD methods alone are generally considered unsuitable for full transient analysis of hill climb, key-off, fan-on, fan-off scenarios. The computation time to solve the fully transient solution remains prohibitive. Instead, many leading teams employ a series of analyses combining the two codes.
The first analysis is nearly always carried out in RadTherm. A transient analysis using rough estimates for fluid temperatures produces an initial distribution of temperatures over time. The surface temperatures from RadTherm are then exported at key time steps, such as during cruise, after key off, fan on, etc into a Patran neutral file. The surface temperatures are paired with mesh geometry information to allow mapping to the higher-resolution CFD mesh of the same vehicle system.
Because CFD codes handle steady state flow schemes easily compared with transient, a series of steady-state CFD "snapshots" is produced, based on the initial RadTherm run.
Many CFD codes can import the Patran neutral file from RadTherm as a boundary condition profile, assigning wall temperatures to match the results from RadTherm. Each key phase of the overall transient run is analyzed separately in the CFD code, and flow values and fluid temperatures are computed. To translate these values back to RadTherm, the results are translated into fluid temperatures and convection coefficient values at the fluid-wall interface. Geometry information is likewise conveyed, and RadTherm maps the fluid temperatures and convection coefficients to the appropriate elements of the model.
RadTherm imports these steady-state CFD snapshot results at user-defined points in time. In the example presented here, we expect four CFD data sets to be produced -- during cruise, key-off soak, fan on, and fan off conditions. The user therefore imports the CFD data at key points in time to represent the complete series of flow schemes. For providing a continuous but transient convection data set. It should be noted that RadTherm is unique in the ability to combine disparate CFD data sets into a single thermal solution: even distinct domains can be combined, with one collection of CFD results used on vehicle exterior and a separate, distinct CFD data set used for the vehicle interior to study HVAC. Before conducting the subsequent RadTherm analysis, the model parameter display window can be used to view the mapped CFD results as colored values on the model geometry to ensure proper matching and units were employed in both codes.
Learn more about CFD Thermal Analysis
Using the most advanced software tools for modeling fluid flow, ThermoAnalytics can solve your convection heat transfer problems and deliver improved thermal designs. ThermoAnalytics provides both component-level and system-level analysis.
RadTherm analyses can be combined with a CFD code to provide a full three-dimensional flow analysis integrated with RadTherm's three-dimensional radiation and conduction.
We help engineering teams integrate their analysis codes to reflect the interrelatability of structural, aerodynamic, and thermal concerns. For example, we often support development groups with outlines for coupling fluid dynamics codes with thermal analysis in RadTherm.
ThermoAnalytics' team of programmer-engineers develop custom scripts and user routines to simulate physics and systems not efficiently captured by software "out of the box." Complex user routines we develop include models of engines undergoing drive cycles and exhaust plumes impinging on surfaces.
