In all real life flows, the properties of a fluid material vary with pressure and temperature. The degrees of these variations depend on both the fluid itself and the flow regime. Some engineering simulations can assume constant material properties, but compressible effects are considered significant above a Mach number of around 0.3. Hence, in order to model applications such as external gas flows, nozzles and exhaust systems, material modelling techniques are required that can capture these material property variations.
In ANSYS AIM 16.2, we have incorporated the ideal gas model to determine the fluid density using the ideal gas equation of state. AIM also provides users a way to prescribe temperature dependent variations of other material properties (Specific Heat, Dynamic Viscosity and Thermal Conductivity), either by using an algebraic expression or by defining a table of values.
High subsonic flow over a blunt projectile, illustrating density variation and mesh density
Easy access to material modelling choices
In ANSYS AIM, the guided templates allow you to select when compressible effects are important, and this will automatically activate the Ideal Gas model. The material model can be defined per-region, giving unprecedented flexibility for simulating multi-region flows such as a high-speed hot gas flow separated from a low-speed coolant liquid by a thermally conducting solid.
Easily select compressible effects from Fluid-Solid Heat Transfer Template.
The more complex effects of temperature variation on material properties can be easily prescribed using tabular data or temperature-dependent expressions for fluid materials. If the variation is prescribed by a set of data points, these can be entered in a simple table and AIM will then display the variation on a corresponding curve. When using algebraic expressions to define the material property variation, the software provides suggestions for the variable names to aid you, and makes it easy to define complex dependencies.
Post-processing of compressible flows is straightforward, with quantities like density, Mach number and other material properties directly available in the simulation results.
Compressible flow through a nozzle, Mach number displayed on fluid streamlines.
Transonic flow over a wing, Mach number contours
ANSYS AIM 16.2 enables every engineer to model compressible flow scenarios with unprecedented ease of use, using best in class solver technology. For more information please visit our website where you’ll find a number of resources.
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