Model a homogeneous gas mixture

This procedure assumes that you are aware of all the steps required to define a complete analysis. The steps presented here are additional steps required to model a homogeneous gas mixture.

Create a Homogeneous Gas Mixture modeling object

1. Choose Home tab→Properties group→Modeling Objects .

2. In the Modeling Objects Manager dialog box, from the Type list, select Homogeneous Gas Mixture.

3. Click Create.

4. In the Homogenous Gas Mixture dialog box, from the Gas 1 (Primary) list, select the material for the primary gas.

5. From the Gas 2 to Gas 5 lists, select the necessary additional mixture gases.Note: The name you use for the material is used to name the corresponding concentration result set in post processing.

6. In the Mixture Properties — Molecular Diffusion Coefficients group, in the Gas 2 to Gas 5 boxes, type the molecular diffusion coefficients for each of the species you selected in step 5, following the same order.Note that you do not have to type the molecular diffusion coefficient of the primary gas.

7. In the Mixture Properties — Turbulent Schmidt Numbers group, in the Gas 2 to Gas 5 boxes, type the turbulent Schmidt numbers for each of the species you selected in step 5, following the same order.Note that you do not have to type the turbulent Schmidt number of the primary gas.

8. Click OK.

9. Click Close.

Define a gas mixture in a 3D mesh collector

1. In an active FEM file, choose Home tab→Properties group→Mesh Collector .

2. In the Material group, from the Type list, select Mixture.

3. From the Mixture list, select a Homogenous Gas Mixture modeling object, or click Create Modeling Object to define a new Homogeneous Gas Mixture modeling object.

4. Click OK.

Specify initial or ambient conditions for a fluid volume with a Homogeneous Gas Mixture material

1. Choose Home tab→Loads and Conditions group→Initial Conditions .

2. From the Type list, select Initial Mixture — 3D Flow.

3. Select the bodies representing the flow volume on which to apply the initial mass fractions of the species present in the mixture.

4. In the Mixture Mass Fraction box type the corresponding mass fraction of the species used in the flow volume you selected.The mass fractions are defined for all gasses, including the primary gas.

5. Click OK.

Define mixture contents in an inlet boundary condition

See Create a Flow Boundary Condition for other options you need to set in the Flow Boundary Condition dialog box.

1. Choose Home tab→Loads and Conditions group→Flow Boundary Condition .

2. In the External Conditions group, click Create Modeling Object to define an External Conditions modeling object. In the External Conditions dialog box, you can use ambient values or define temperature, humidity, and turbulence values.You must use an External Conditions modeling object whenever you use a Homogeneous Gas Mixture modeling object in a flow boundary condition.

3. In the Mixture group, select Specify Fractions from the Homogeneous Gas Mixture list.

4. In the Mixture Mass Fractions box, type the corresponding mass fraction for the species present on the flow face you selected.The mass fractions are defined for all gases including the primary gas.

5. Click OK.

Modify global ambient or initial conditions to model mixtures

1. In the Simulation Navigator, right-click the Solution node and choose Edit.

2. (Optional) On the Initial Conditions tab, do the following to specify the species initial condition for the whole flow volume.From the Initial Conditions list, select Uniform.In the Humidity, Tracer Fluids, and Mixtures group, from the Mixtures list, select Specify Fractions. In the Mixture Mass Fractions box, enter the global corresponding species of the mixture. Mass fractions are defined for all gasses, including the primary gas.

3. (Optional) In the Ambient Conditions tab do the following to specify the species initial condition for the whole flow volume.In the Humidity, Tracer Fluids, and Mixtures group, from the Mixtures list, select Specify Fractions.In the Mixture Mass Fractions box, enter the global corresponding species of the mixture. Mass fractions are defined for all gasses, including the primary gas.

4. Click OK.

5. Click the Result Options tab.

6. Select the Humidity, Tracer Fluids, and Mixtures check box.

7. Click OK.

Add mixture result sets, solve, and view mixture results

1. Choose Home tab→Solution group→Solve .

2. In the Simulation Navigator, double-click the Results node.

3. In the Post Processing Navigator, double-click the GasName[material ID]_M#G# — Element-Nodal node.In the Post Processing Navigator, there are result nodes for each species of the mixture except the primary gas. The result nodes are named GasName[material ID]_M#G# — Element-Nodal where:GasName is the name of the fluid material you set in the Fluid Material dialog box.M# represents the label of the Homogeneous Gas Mixture modeling object.G# represents the ID of the specific gas in the mixture, ranging from 2 to 5.

Simulation 1
Solution 1 Results
Velocity — Element-Nodal
...
Gas 2[2]_M5G2— Element-Nodal
Scalar
Gas 3[3]_M5G3— Element-Nodal
Scalar
Gas 4[4]_M5G4— Element-Nodal
Scalar
Gas 5[5]_M5G5— Element-Nodal
Scalar

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)

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

Fluid materialsfor heat transfer and flow analyses

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

Model a homogeneous gas mixture, Simcenter 3D 2021.1 Series

© 2020 Siemens

window.mainLanguage="en_US"

window.delivId=""

window.projectId=""

MathJax.Hub.Config({ TeX: { extensions: ["autoload-all.js"] }, tex2jax: { displayMath: [ ] }, "SVG": { scale: 125 } });