Connections to CFD

Integrations with Third-party CFD Software

CFD software can be used to augment the capabilities of the Thermal Desktop (TD) suite. See the Compare to CFD tab of the FloCAD product page for more information on when to use CFD, and when to use FloCAD fluid network solutions.

Often, CFD provides heating rates, but it can also provide far-field or local temperatures paired with convection coefficients. Such inputs help characterize external flow fields for TD vehicle models. The "BC Mapper" is available to help with this common task.

Or perhaps you have a unique flow modeling situation, such as a star-shaped inlet, a unique valve design, a cable inside of a pipe, or a custom heat exchanger design. You need to perform system-level transients or other high-level simulation tasks, but you lack test data or other ways to approach the characterization of such a flow component. Preliminary CFD runs can help characterize the flow losses or heat transfer performance in preparation for a FloCAD study.

In some cases, you need the unique capabilities of both Thermal Desktop and CFD working together on a tough problem. That's possible too!

Sequential Solutions

Using CFD Predictions for Thermal Inputs: Boundary Condition Mapper

The Boundary Condition Mapper, or BC Mapper, applies boundary conditions to Thermal Desktop models through a mapping process. The boundary conditions that can be applied from CFD are temperature-dependent heat flux, temperature applied to boundary nodes, or convection coefficient paired with a boundary temperature. All of the boundary conditions can vary with time. The mapping process allows data from a dense surface mesh typically used for CFD calculations to be applied to a much coarser thermal model. The mapping can be interpolated or nearest-point.

The source of the boundary conditions can be anything that the CFD code can calculate whether it's aeroheating of a crew capsule, exhaust from a jet engine on a wing, or thruster impingement on part of a spacecraft. The CFD application can focus on what it does best and Thermal Desktop can focus on the underlying thermal solution, allowing for evaluation of various thermal protection systems or flight profiles.

You can learn more about the BC Mapper in the video lesson Applying CFD Data to Thermal Desktop Models.

Using CFD Predictions for FloCAD Inputs

When correlations or test data are not enough to cover a custom component or unique situation, you can use a CFD solution to develop inputs for use in FloCAD.

For example, you might use CFD runs to define a flow split, a pressure or velocity boundary condition, an effective loss or heat transfer coefficient (perhaps for a unit cell of a heat exchanger). Often, the CFD studies will be parametric, perhaps varying flow rate or inlet temperature to provide the responses necessary for the system-level or cycle-level simulation in TD/FloCAD.

Using CFD predictions as inputs to SINDA/FLUINT enables modeling of transients, parametric solutions, optimization, calibrations to test data, tabulation-style loss components, two-phase flow solutions, system-level or component-level heat exchanger simulations, and so forth.

Co-Solved Solutions

Sometimes, you need a tighter connection between TD and CFD: a co-solved solution, where both programs are working together to arrive at a steady state answer or a transient profile.

This requirement can arise in internal flows, such as natural convection within a complex cavity whose shape is not covered by the built-in set of TD correlations. Or perhaps you have built and calibrated a TD/RadCAD model against vacuum chamber data, but now need to simulate GN2 cooling before launch.

Currently, you can co-solve CRTech Thermal Desktop and Ansys Fluent CFD. Two sample problems demostrate and validate this usage:

This is an active area of development. Keep watch for even more connections in the future!