Steady State Heat Transfer Analysis- Convective heat transfer coefficient in SIMLAB

Sivaprakash_V
Sivaprakash_V Altair Community Member
in Community Q&A

Description: I have been performing a heat transfer analysis for Plastic Box molded with steel plate. My aim is to find the heat transfer when I apply the Temperature as 50 deg/c in one face of the steel plate.

For This Analysis, I am using SIMLAB. I meshed the model, created a Heat Transfer Solution and Assigned the Materials.

In Boundary condition, I applied the Input temperature in one of the faces of Steel Plate.

Then I have Some doubts in Boundary conditions.

1) Here How to assign the initial temperature for plastic and steel parts.

2) If I apply the temperature values as ambient temperature Under Temperature ribbon in remaining faces except the input temperature applied faces, The software will show the Heat transfer contours or not ?

3) I saw the tutorials from Altair How to Channel: Linear steady state Heat Transfer analysis. Based on this tutorial, They used Engine cylinder assembly. In that, they applied the heat flux in the cylinder area and applied the convection in the fins area. Why do they use convection in fins area for conduction problem statement and how that values are calculated? Without applying the convection why that analysis was not shown any contours ?

4) In my case, How can I calculate the heat transfer convective coefficient value for plastic material?

I attached the image for reference:

111.jpg

Here the Green Box is Plastic and the yellow one is Steel Plate.

Product/Topic Name : ALTAIR SIMLAB as PREPROCESSING & SOLVER as OPTISTRUCT.

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Best Answer

  • Adriano_Koga
    Adriano_Koga
    Altair Employee
    Answer ✓

    again…the value for the coeficient depends on a few aspects of your convection, and i'd say that you could use the reference values from literature.

    If you want to actually calculate the coefficient, i believe you would need to try to calibrate it using transient and also having some experimental data. Or using a CFD analysis to calculate the forced convection coefficient.

Answers

  • Adriano_Koga
    Adriano_Koga
    Altair Employee

    hi,

    good description on the problem. :)

    i'm not sure it is valid to apply initial condition in a steady state analysis. In a transient analysis it would be here:

    image.png

    in your model, the mesh of the plastic part and steel are connected node-to-node? if yes, then there is conduction between these 2. If not, you could create a contact (FREEZE) between these 2 in order to promote conductive heat transfer there.

    From your description, you're applying a fixed temperature at one face of the steel block.

    What about the other faces? are they in contact with ambient temperature? is there convection there?

    The energy balance and heat fluxes depend a lot on these conditions, right?

    Maybe try describing what physically you're trying to simualate.

  • Sivaprakash_V
    Sivaprakash_V Altair Community Member

    Hi,
    Thanks for your reply.

    My Model was not connected between node to node and I created a Tie contact between two bodies during the solution creation.

    Yes, I applied the Fixed Temperature as INPUT Temperature at one faces.
    The Other faces are contact with ambient Temperature or air.

    Actual Problem statement:
    I have a Plastic Box Molded with Steel Plate. Here I want to perform the Heat Transfer analysis by applying the Temperature (50 deg/c) at one face of the plate to see the heat transfer. Then use this output as Thermal loading and perform the structural analysis to find out the Stresses and deformation in plastic box due to thermal expansion of that steel plate.

    In my case, How can I calculate the heat transfer convective coefficient value for plastic material?
    If calculated, where can I apply that value? By clicking faces or entire plastic body ( by picking solid).

    Thanks & Regards,
    sivaprakash V.

  • Adriano_Koga
    Adriano_Koga
    Altair Employee

    i believe that you need to knwo the convective coefficient upfront. for steel i believe this would be a standard value, depending on if it is natural or forced convection.

    If needed you could tune your real convection coefficient by performing a transient analysis and checking how long does it take to cool down from a certain temperature. If the coefficient is too high, the temperature will drop faster..if it is too low, it would take longer to cool down.

    image.png

    for the 2 step analysis, you could use the attached file as example.

    sample_heat2.slb
  • Sivaprakash_V
    Sivaprakash_V Altair Community Member

    Hi ,

    Thanks for your reply.
    I want to know how to calculate the convection heat transfer coefficient for particular material like steel, plastics etcc. Because I can use it for my other application.

    For performing coupled Thermal structural analysis, I use your model and also I saw youtube tutorial from Altair How to channel.

    To find the actual coefficient value, I will perform transient analysis. Does Transient analysis solution give output as Convective heat transfer coefficient. If I calculated, can I use that value for Steady state analysis.
    What are the boundary condition should I use to perform this analysis?

    I use this Convective heat transfer coefficient value for assigning as Convection input.

    Thanks & Regards,
    Sivaprakash V.

  • Adriano_Koga
    Adriano_Koga
    Altair Employee
    Answer ✓

    again…the value for the coeficient depends on a few aspects of your convection, and i'd say that you could use the reference values from literature.

    If you want to actually calculate the coefficient, i believe you would need to try to calibrate it using transient and also having some experimental data. Or using a CFD analysis to calculate the forced convection coefficient.

  • Sivaprakash_V
    Sivaprakash_V Altair Community Member

    Hi, Thanks for your answers.
    I will go through it.


    Thanks & Regards,
    Sivaprakash V

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