10 Replies Latest reply on Oct 18, 2016 9:58 AM by Antonis Biratsis

    How do i create a "dummy" part for an external flow simulation ???

    Antonis Biratsis

      Hi guys.

       

      I want to create a "dummy" part outside my cube and i want to use that area as local initial size , in order to calculate the drag force on a 2D and a 3D cube.

      Also can i create multiple "dummy" parts around my cube ? For example i want to make two initial local (one inside the other).

       

      1.Does anyone have some detailed steps in order to do that ?

      2. How can i achive a specific cell size in that area ? For example i want all the area around the cube to be 0.1m cell size. Is that possible ?

       

      Thank you in advance.

        • Re: How do i create a "dummy" part for an external flow simulation ???
          Amit Katz

          "Dummy" parts are solid geometry that you manually disable in your projects. If you right click on "Input data" in the project tree and select "Component Control" you can see a list of all the geometry in your assembly/part file. Here you can select/deselect parts to be included as physical geometry in the simulation. Parts that are deselected will be "dummy geometry" that you can use for reference. Note that you can choose to disable individual solid bodies in a multi-body part file as well, simply expand the "+" mark next to the file name.

           

          Capture.PNG

           

          As for cell size, you need to go back and re-read the tutorial on creating meshes. Your local mesh regions will be areas where cells are split down (by factors of 1/2, 1/4, 1/8 etc...) from the basic cell size. You can set your basic cell size in the mesh menu, advanced options.The rest is simple math.

            • Re: How do i create a "dummy" part for an external flow simulation ???
              Antonis Biratsis

              Thank you for your quick response Amit.

               

              Regarding the cell size, can you show me a picture from the mesh menu (advanced options) how can i check that the local initial size of the cell is for example 0.01m ? I have been searching a lot in the mesh menu and i am not sure how to do that.

               

              Also , is there any way that we can insert some sort of "inflation" (like Ansys Fluent) on the object walls in order to caption a better flow result near the walls.

               

              My first thougth is with a very very small "dummy" part (for example 10mm). In your experiense will this be a good way to do it ?

               

              Thank you in advance.

            • Re: How do i create a "dummy" part for an external flow simulation ???
              Amit Katz

              I'm not sure about "inflation", you'll just have to manage the mesh carefully near the walls.

               

              To set your basic mesh size you need to go to the meshing menu and click on "Manual":

              Capture.PNG

              You can toggle here between cell count and cell size (something I just learned now! )

                • Re: How do i create a "dummy" part for an external flow simulation ???
                  Antonis Biratsis

                  This option is probably on SolidWorks 2016 , because on the Flow Simulation of SolidWorks 2015 there is no such menu......

                   

                  I will try to find a way to set the mesh very close to the body.

                    • Re: How do i create a "dummy" part for an external flow simulation ???
                      Bill McEachern

                      Most of it is in 2015....turn off automatic setting in the mesh settings. This will get you a similar panel for the global mesh. I believe it is new in 2016 to be able to set up a basic mesh (as is done in the global mesh settings) in a flow volume used as a mesh control.

                      You can pick the volume (or face or an edge or a vertex)  for a mesh control and then start at something modest (2, 3, 4 or 5) and test the mesh to see if it gets fine enough for what you need. There are many other controls you can use when you disable the automatic settings. There is a great section on the mesher in "Solving Engineering Problems" document in the directory with the tutorial manual and the technical reference. In any event you will not be able to specify a specific cell size. The program doesn't work that way and it is not a short coming in my humble opinion, though on occasion it could be handy to aid in post processing but I have only come across it once in 18 years of using the program and even then there were other ways to get what was wanted.  If you think you need a very specific cell size you need to ask yourself why you need it for the problem at hand. Then you need to research how the program works and see if it still makes sense to be asking for a specific cell size.