Fluid materials for heat transfer and flow analyses

Fluid materials let you define material properties for fluids, including liquids and gasses. Fluid type materials are not typically used in structural analyses.

Analyses

Heat transfer and flow analyses use fluid materials, which are assigned to elements.

• The flow solver uses fluid material properties to model 3D flow on solid elements.

• The thermal solver uses fluid materials to model 1D flow on 1D duct elements.

Applications of fluid materials

Elements with fluid material properties can:

• Conduct heat.

• Radiate heat.

• Convect heat to elements with thermal material properties.

• Transport tracer fluids or particles in flows.

Equations of state

An equation of state is a constitutive equation which provides a mathematical relationship between thermodynamic state variables for a given material.

The following equations of state are available in the flow solver:

• Incompressible fluid, where density is constant

• Density that varies only with temperature

• Classical ideal gas law

• Redlich-Kwong real gas equation of state

The classical ideal gas law and Redlich-Kwong real gas equation of state require that you define a gas constant for the fluid material. When you define a gas constant, the density varies with pressure and temperature.

You should use the Redlich-Kwong real gas equation of state only in the following cases:

• At high pressures as it is more realistic than the ideal gas law.

• When the ratio of the pressure to the critical pressure is less than about one-half of the ratio of the temperature to the critical temperature:

The flow solver always uses the gas constant, Rs, for the density calculation. To override this and specify a constant density value or to specify density as a function of temperature, you must clear the Gas Constant box on the Other Physical Properties tab in the Fluid Material dialog box.

Where do I find it?

Application	Pre/Post
Prerequisites	Simcenter 3D Multiphysics, Simcenter 3D Thermal/Flow, Simcenter 3D Space Systems Thermal, or Simcenter 3D Electronic Systems Cooling as the specified solverFEM file as the work part and displayed partType = Fluid
Command Finder	Manage Library Materials Manage Materials Assign Materials Physical Properties

How do I

Define a gas using the Redlich-Kwong equation of state

Define a bivariate fluid material property

Define a bivariate fluid material property using a generic entity (legacy)

Model a homogeneous gas mixture

Define a Non-Newtonian Fluid

Model a tracer fluid

Learn more

Fluid material conversion

Bivariate fluid material properties

Immiscible Fluid Mixture

Homogeneous Gas Mixture

Non-Newtonian Fluid

Tracer Fluid

Look up more details

Modeling multiple fluids

Multiple Fluid materials

CSV file format for bivariate fluid material properties (legacy)

Quick links

Thermal/Flow, Electronic Systems Cooling, and Space Systems Thermal

Simcenter 3D Thermal/Flow, Electronic Systems Cooling, and Space Systems Thermal boundary conditions

Command reference

Pre/Post video examples

Bulk Entry Descriptions

Simcenter 3D tutorials

Browse Simcenter 3D help by product area

Fluid materials for heat transfer and flow analyses, Simcenter 3D 2021.1 Series

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