Preprocessing

Preprocessing

Structured mesh

    • shaheen wahab
      Subscriber

      Hello everyone,


      I have a rectangular channel of 200m x 25m x 2m dimension. The bottom of the channel has a hump of approximately 30 cm in height and extends over 30 m at the center. I am working on Dynamic mesh where the hump has to propagate over the channel. I have divided the channel horizontally at Z=1m. Now I want to construct a structured mesh but I fail every time, as I get some slightly tilted elements at the bottom. I tried so many methods, but not able to figure out the actual approach that would lead me to construct a perfect structured mesh.


      Earlier I constructed a structured mesh in the same rectangular channel with the body divided into 3 parts (the hump being a separate part altogether, the right of the hump and the left) But I don't know what exactly I should do to get a structured mesh. 


      Under any circumstance, I am not getting a structured mesh. The mesh in the image is the default mesh generated without any method.


      I would be really grateful if you could help me in this regard.


      Thank you 


      With regards


      Shaheen Akhtar Wahab



    • Aniket
      Ansys Employee

      shaheen wahab


      1. You can Split the bodies vertically (and create multibody part so that those will share faces) to get straight edges


      2. You can also use "Hard" Edge sizings on the all the edges based on the number of divisions and make sure that those align properly with the edge on the other side.

    • shaheen wahab
      Subscriber

      Dear Aniket,


      Thank you so much for your reply. I already tried that (splitting the body vertically into 3 parts). I got a structured mesh, but in that case, the Dynamic mesh results were not good, so I decided to split the body horizontally and now I am not getting good results (bad actually)!


      Thank you 


      With regards


      Shaheen 




       


       


       

    • Aniket
      Ansys Employee

      shaheen,


      Did you set edge sizing behavior to "Hard"?

    • shaheen wahab
      Subscriber

      Dear Aniket, 


      Yes, I did set it to hard. Now I am using Multizone method, the tilted elements seem to have gone but it seems there are a lot of biased elements appearing on the all the other faces. 


      I have used the Multizone method (on the upper and lower body) and set Sweep element size to 0.5m. I have selected "Source" as the bottom surface (which comprises of 3 surfaces, and I cannot merge them as it creates a different surface altogether)


      I then used edge sizing using biased factor as 5 and no. of division 7 in order to get the lowest layer of 5cm.


      I don't understand from where another "bias" appears on other surfaces  


      I have used one edge sizing on two edges and another edge sizing on the other two (as the bias reverses and I don't understand why)


      Thank you 


      With regards


      Shaheen 


       





    • shaheen wahab
      Subscriber

      Dear Aniket, 


      Thank you for your tips. They were helpful. I could solve the problem. 


      The steps are as follows: 


      1. Multizone (I changed the Surface mesh method to Uniform, which eliminated all those unwanted biases that I mentioned earlier)


      2. Edge sizing (using Biased) for the lower edge separately starting from the 5cm thickness. For the upper edge, I used a similar bias with the height of the first layer slightly greater than the last layer of the previous bias. 


      3. Another Edge sizing at the top edge of the channel (along the longer edge) 


      And that worked!


      Thank you


      With regards


      Shaheen  

    • psh1988
      Subscriber
      Dear Aniket
      Could you please tell me how can i develop mesh like this?
    • psh1988
      Subscriber
      Unfortunately i have forgotten my password and it is weird that i can not receive the reset password email in my inbox,what should i do?
    • psh1988
      Subscriber

       Oh, I received my password. So I can use my laptop options to attach geometry along with my text. Could you please tell me how can I develop a mesh like this ?


       


      I used multizone for the parts but my mesh at its best looks like the below.


       


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