Fluids

Fluids

External flow dynamics

    • tumulpurwar
      Subscriber

      i am simulating hull drag by using steady state by using 1,2 million polyhedracells,i have ran 5000 iterations, but still residuaals and drag force graph shows big fluctuaations, thus not  converged yet.

      i am using 26 meter length hull,with 4 core license.....is any expert can tell y seeing residuals, whether such residual graph are correct or not?

      i used non structurall mesh of polyhedrara, which is correct.

    • RK
      Ansys Employee

      Hello, 

      What is the settings you are using? Can you also please post some pictures of the contours and residual plots? 

    • tumulpurwar
      Subscriber

    • tumulpurwar
      Subscriber

       

       

    • RK
      Ansys Employee

      What about settings?

    • tumulpurwar
      Subscriber

    • tumulpurwar
      Subscriber

    • tumulpurwar
      Subscriber

    • tumulpurwar
      Subscriber

    • tumulpurwar
      Subscriber

       its pressure inlet & outlet boundary condition i applied,rest are symmetry and hull as wall.

      Any feedback please

    • tumulpurwar
      Subscriber

      @RK Any feedback from your side? 

    • Rob
      Ansys Employee

      Are you using the Open Channel options in VOF? The boat looks to be above the water level. 

    • tumulpurwar
      Subscriber
      Yes open channel (flat) No waves My iso surface is in wrong location, sorry in photo What can be than reason of not converge yet
    • Rob
      Ansys Employee

      If it's in the wrong location, how did you assign the inlet & outlet heights, and are you running transient? How did you initialise the water level?

    • tumulpurwar
      Subscriber

      Wrong only is iso surface in phase contour, which I created after initialization step. 

      Inlet outlet heights are correct. 

    • tumulpurwar
      Subscriber

      I am running steady (pseudo transient) 

      I just initialize with inlet(hybrid) 

      Not did any patch before initialization of water air

    • Rob
      Ansys Employee

      OK, so you may still be filling the domain. With VOF it's important to patch the water level. Also, pseudo transient isn't real transient so the solver may struggle. 

    • tumulpurwar
      Subscriber

      Ok thanks

    • tumulpurwar
      Subscriber

      Hi Rob

      As per you instructions in last comments.

      i tried this time, Transient solver instead of steady solver

      16965 iteration done, still solution not reached to convergence, also this time i have patched water, while doing initialization.

      Can you see these contours and tells why it not converging yet.

      I know from experiment results that my drag force should be 105 KN, but it is coming in anys fluent after simulating for almost 17000 iterations 54 KN.

    • tumulpurwar
      Subscriber

    • tumulpurwar
      Subscriber

    • tumulpurwar
      Subscriber

    • tumulpurwar
      Subscriber