4 Replies Latest reply on Feb 18, 2014 11:52 PM by Jared Conway

    Flow Simulation unexpected result

    Enhao Zhang
    Enhao Zhang Feb 17, 2014 9:33 PM

      Hi

           The attached file is my model.

            I set the heat source(resistor) with a heat generation rate of 60W on each of them.

           Fan speed is set to be 5000RPM on each fan.

           So after simulation finished, I got a peak avg temperature of 500 Celsius at iteration 68, and a final avg temperature of 230 Celsius on the heat sources.

           I was expecting to get something like under 100 degrees Celsius, is there anything wrong on the setup?

        • Re: Flow Simulation unexpected result
          Jared Conway
          Jared Conway Feb 17, 2014 11:21 PM (in response to Enhao Zhang)

          Have not looked at the model.

           

          But have you looked at the fan flow rates? Are they what you expect?

           

           

          To check your setup, can you elaborate on the test environment and what assumptions your analysis makes. That may help you understand the source of error or expected error.

           

          It may also be helpful to know what you are comparing your simulation against and how it may differ from the simulation.

            • Re: Flow Simulation unexpected result
              Enhao Zhang
              Enhao Zhang Feb 18, 2014 1:50 PM (in response to Jared Conway)

              hi Jared

                   I assume the test performs under default environment conditions which temperature set to be 20.05 celsius and pressure set to be 101325 pa.

                   Material of heat source and heatsink is copper, the default material is glass insulator.

                   The entrance surface and exit surface of the box that wraps around the setups are set to have environmental pressures

                   The initial mesh is in default setting of solidworks(level 3) I didnt change anything in there

                   I didnt consider any gravity. Walls are set to have a 5.5 W/m^2 heat transfer coefficient with outer environment(i assume the system means the outside of computational domain)

                   I don't know what other assumptions that you may need.

               

                   I also did run the the flow trajectories on the air entrance surface. The motion of the air seems to be correct. So even though I did not check the flow rate of the fan, I think the they perform normally by roughly looking at the speed of air entering the heatsink.

                   So I am in a heatsink designing process. There is no external reference like experimental results for comparing.  Can you help to check is there any obvious mistakes that i made in the model that lead to this result?