height vs temperature function in a multiplier

Gart04
Gart04 Altair Community Member
edited September 2022 in Community Q&A

Hi

I need to create a height vs temperature function in a multiplier (affected in a stagnation pressure), i really don't know how to do that. I need a curve like this :

Z height(m) Temperature (K)

0.1                273.16

0.2                283.16

0.3                285

...

In a multiplier i only have xvariable as time, cyclic time, time step or time increment

Thanks a lot

Best regards

 

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Best Answer

  • acupro
    acupro
    Altair Employee
    edited September 2022 Answer ✓

    The multiplier function is, indeed, only for changing items as a function of time or time step.

    You'll probably want to use an Advanced BC (pull-down under the Boundaries group in Flow ribbon) and use Nodal Boundary Condition (NBC in panel) to define the temperature.

    Variable = Temperature
    BC Type = NBC
    Type = Piecewise Linear

    Select your Curve Fit Variable, then input the desired values.  (Coordinate is location at current time, Reference Coordinate is location at time = zero.  If there is no mesh movement, they are the same.)  You'll specify that in terms of absolute position, not relative to 'edge' as I'm assuming you have indicated above.

    Be careful, as this can sometimes remove the main BC from the surface.  (Behavior to be fixed in 2022.2 release.)  You may need to create a Surface Monitor for the surface, use that as a guide to replace the main BC in the input file, then run from command-prompt or Compute Console.

Answers

  • acupro
    acupro
    Altair Employee
    edited September 2022 Answer ✓

    The multiplier function is, indeed, only for changing items as a function of time or time step.

    You'll probably want to use an Advanced BC (pull-down under the Boundaries group in Flow ribbon) and use Nodal Boundary Condition (NBC in panel) to define the temperature.

    Variable = Temperature
    BC Type = NBC
    Type = Piecewise Linear

    Select your Curve Fit Variable, then input the desired values.  (Coordinate is location at current time, Reference Coordinate is location at time = zero.  If there is no mesh movement, they are the same.)  You'll specify that in terms of absolute position, not relative to 'edge' as I'm assuming you have indicated above.

    Be careful, as this can sometimes remove the main BC from the surface.  (Behavior to be fixed in 2022.2 release.)  You may need to create a Surface Monitor for the surface, use that as a guide to replace the main BC in the input file, then run from command-prompt or Compute Console.

  • Gart04
    Gart04 Altair Community Member
    edited September 2022
    acupro_21778 said:

    The multiplier function is, indeed, only for changing items as a function of time or time step.

    You'll probably want to use an Advanced BC (pull-down under the Boundaries group in Flow ribbon) and use Nodal Boundary Condition (NBC in panel) to define the temperature.

    Variable = Temperature
    BC Type = NBC
    Type = Piecewise Linear

    Select your Curve Fit Variable, then input the desired values.  (Coordinate is location at current time, Reference Coordinate is location at time = zero.  If there is no mesh movement, they are the same.)  You'll specify that in terms of absolute position, not relative to 'edge' as I'm assuming you have indicated above.

    Be careful, as this can sometimes remove the main BC from the surface.  (Behavior to be fixed in 2022.2 release.)  You may need to create a Surface Monitor for the surface, use that as a guide to replace the main BC in the input file, then run from command-prompt or Compute Console.

    Hi

    thanks a lot for your quick answer, I implement your advice.

    Best regards, Nicolas

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