4 Replies Latest reply on May 1, 2012 2:13 PM by Gintautas Nesvarbu

    External flow simulation problem (urgent)

    Gintautas Nesvarbu

      Hi to all,

       

      I'm new in here and I need help. I've spent a lot of time trying to find an answer to my problem, but I still haven't found one, so this forum is my last hope. Any help will be highly appreciated.

       

      Problem

       

      I've got a pipe which should take an external air flow simulation test (simulating pipe in the wind tunnel). The problem is that the air flow is not going inside of the pipe, or if it goes than it is like 3-5 pipes out of 1000. I know that it deffenetly has some airflow inside, as I've done the test in the scale wind tunnel. I'm adding a screenshot, hoping that it will explain problem better.

       

      solidworks forum.jpg

      My flow conditions are inlet z = -10m/s at standart atmospheric pressure. Thank you for all the answers in advance.

        • Re: External flow simulation problem (urgent)
          Igor Isayev

          Gintautas,

           

          What is the goal for the study - to analyze the pipe externally or internally?  Or do you want to calculate the ratio between the amount of flow going into the pipe compare to amount of flow passing through wind tunnel ? 

           

          3D Trajectories option should not be used to make any conclusion.  If you would like to simulate the flow passing through the pipe , you need to have some lids that are placed inside the pipe and normal to flow , disable them using Component Control. Once they are placed, you may create some Surface goal(s) selecting face on those Lid(s) , check any flow parameters ( like volume/mass flow rate ,velocity, pressure,etc).  When the study is converged , you can generate some goal results that were already pre-set , or select the same faces on lid(s) and generate result (excel) file for the parameters you look for.  

           

          Good Luck !

            • Re: External flow simulation problem (urgent)
              Gintautas Nesvarbu

              The goal for the study is to analyze pipe internally but the simulation must be external (as far as I understand). Like I mentioned before I've done wind tunnel testing and the values I've got was 7.5m/s at the outlet when inlet velocity is equal to 10m/s. So as far as I understand to simulate wind tunnel testing I need to use external flow simulation instead of an internal one. But the problem is as You can see in the picture air flow is not going into the pipe, or if it is going it's just few pipes out of 1000. I've created lids and disabled them to get the surface goal like You said, but when the air is not going into the pipe I don't get correct goals values.

               

               

              I've tried to use internal and I've got wrong results, such as 300m/s at the outlet. I'm almost 100% sure I've done it right, as I have used internal simulation for intake manifolds, before and there was no problems.

            • Re: External flow simulation problem (urgent)
              Kevin De Smet

              I'm not sure what the problem is, but as a last resort, you could try modeling a fairly large cylinder around your geometry, then you can run it as an internal flow analysis.

               

              I'd also make sure your mesh grid is fine enough so the flow does not have any resistance going in.