Derived Values – Mach number

Derived Values – Mach number

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How to calculate Mach number in COMSOL Multiphysics

In high speed flows, Mach number is a vital character in investigation of the fluid flow. For this aim in COMSOL Multiphysics, Derived Values has been employed and Simulation of Supersonic Air-to-Air Ejector CMS is used to illustrate this.

Derived Values

Check if the average of the Mach number at the primary inlet is similar to the value defined in Inlet 1.

Line Average 1

  1. In the Results toolbar, click More Derived Values and choose Average>Line Average.
  2. In the Settings window for Line Average, type Mach number, primary inlet in the Label text field.
  3. Locate the Data section. From the Dataset list, choose Study 1/ Adaptive Mesh Refinement Solutions 1 (sol3).
  4. From the Parameter selection (Refinement level) list, choose Last.
  5. Locate the Selection section. From the Selection list, choose Primary inlet.
  6. Locate the Expressions section. In the table, enter the following settings:
ExpressionUnitDescription
hmnf.Ma1Mach number
  • Click Evaluate.

Derived Values

Check if the average of the Mach number at the secondary inlet is similar to the value defined in Inlet 2.

Line Average 2

  1. In the Results toolbar, click More Derived Values and choose Average>Line Average.
  2. In the Settings window for Line Average, type Mach number, secondary inlet in the Label text field.
  3. Locate the Data section. From the Dataset list, choose Study 1/ Adaptive Mesh Refinement Solutions 1 (sol3).
  4. From the Parameter selection (Refinement level) list, choose Last.
  5. Locate the Selection section. From the Selection list, choose Secondary inlet.
  6. Locate the Expressions section. In the table, enter the following settings:
ExpressionUnitDescription
hmnf.Ma1Mach number
  • Click Evaluate.


CMS
CMS Website
Computational Modeling and Simulation is the simulation center of Acamech that models Mechanical Engineering Problems, especially Multiphysics Simulation; including Fluid Flow (CFD), Structural Mechanics, Acoustics, Heat Transfer as a unique Multiphysics problem. We use COMSOL Multiphysics, MATLAB, and Autodesk Inventor.

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