3 Replies Latest reply on Aug 20, 2015 8:48 AM by Amit Katz

    Multiple Questions About Flow Simulation

    Jameson Gavac

      Hey everyone, I've been having some issues trying to use Flow Simulation, and I have a couple questions. I'm working on modelling how air would flow and the pressure differentials inside of a CVT cover. Since we are having power loss because of excess heat, we are exploring a few different ways to do this. One of them that I am working on now, is having an alternator fan attached to the primary clutch. I've been learning flow sim along the way, but I've got some problems.


      First off, when using the detailed models of the primary and secondary clutches that the company we buy from provided us, I am unable to select them to assign a rotating region. From what I can tell, it has something to do with the complexity of the part? Because if I use a completely smooth dummy model (no fan on the primary), I can assign rotating regions no problem and the simulation will run. Unfortunately that doesn't do me any good, since the dummy models are a lot different from the actual parts. The clutches have a lot of features and gaps where air will get chopped up, in addition to having the fan on front moving air.


      These are the models I'm trying to use

      Primary and secondary no case.PNG


      The case that encloses them

      With case.PNG


      These are the dummy models that work with flow sim. Primary on the left (notice no fan), and secondary on the right.




      Second off, when I run the flow sim with dummy parts, the flow trajectories originate in the middle of the primary instead of the assigned inlet, the trajectories do not go to the assigned outlet, and they frequently clip through my parts. I can't figure out why this would be happening, so any insight would be helpful.


      Notice the flow is starting in the middle of the secondary, instead of coming in the inlet (cap in front of primary). The fan is attached in this one, but the model isn't rotating.

      Flow start.PNG



      Here we can see the massive amounts of clipping through the pulley halves on the secondary, as well as where the spring body would be.

      flow clipping.PNG


      If anyone could help, I would greatly appreciate it



        • Re: Multiple Questions About Flow Simulation
          Jared Conway

          would recommend you go through the documentation first


          C:\Program Files\SOLIDWORKS Corp\SOLIDWORKS Flow Simulation\lang\english\Docs


          the rotating regions should be very simple models, that is the fluid region that will be rotated essentially.


          and i'm not sure if this is an educational project or a commercial project but you may want to check with your reseller that these are valid rotating regions. if we were taking on a consulting project or mentoring project with them, i would want to check with the developers on whether rotating regions wuold work or if i would need to use sliding mesh in 2015.

          • Re: Multiple Questions About Flow Simulation
            Robert Futch

            I've also been having trouble with clipping through some very thin solid parts in my flow simulations. I've been searching for a way to increase the resolution or something to prevent this problem.

            • Re: Multiple Questions About Flow Simulation
              Amit Katz

              Your rotating "dummy" models should look simple, they must be bodies of revolution to work correctly with the software. All they represent is the volume in your geometry that will be rotating. If you assign them to a sliding mesh type rotating region, the solids inside will rotate as well independent of the rest of your geometry.


              As for flow trajectories clipping, I see that sometimes as well, when I have very complex geometry. I'm not sure what it means, it may simply be a result of the interpolation of the flow paths. As for where they start and end, that depends on the surface you pick to calculate them from and the time and length constraints in the definition of the trajectories.