13 Replies Latest reply on Apr 14, 2016 4:27 AM by Patrk Rećko

    Jet ski pump solver terminated

    Patrk Rećko

      Hello everyone,
      I am new on this forum so firstly let me introduce myself. My name is Patryk and I am a student of Mechanical engineering in Bialystok, Poland.
      I'm working on my school project which is a flow in jet ski drive, an example of axial water pump. My problem is that I getting an error at about 4500 iteration (~2/4 travels): "Solver abnormally terminated! Please contact the support service", but when I'm solving the same simulation but on scaled model, two or three times smaller, there is no error, solver finishing normally.
      I tried to do internal and external flows, low and high quality mesh and problem is always the same, solver terminates on true scale model, but on two or three times smaller it doesn't.

      I'm working with a cavitation model turned on and rotating region.
      I noticed that a while before error appears, density, velocity and pressure suddenly increase their values and sometimes I'm getting an error "Real gas parameters (pressure and/or temperature) are outside the definitional domain of substance properties T<Tmin".
      Anyone could help me ?
      Best regards,
      Patryk

        • Re: Jet ski pump solver terminated
          Amit Katz

          This error is a catch-all error that means "I give up!" for the software. From how you describe your parameters spiking I'm guessing the solution diverges and the model becomes unsolvable. Possibly the mesh is too coarse. And if you need more than 4500 iterations to solve your model, then it's probably not set up correctly. Any chance you can upload your project?

            • Re: Jet ski pump solver terminated
              Patrk Rećko

              Zippyshare.com - 4000RPM cavitation ON.rar
              There is the model with 5000 RPM's set up on impeller (name of folder is wrong), I uploaded it with that invaid result, maybe that will help. I noticed that it doesn't depend on iterations, it always getting an error after 2.1-2.2 travels. Weird thing is that I can solve this case up to 3000RPM even on true scale model but if the value is higher - solver terminates. Finally I want to do this simulation with 8300 RPM's.
              1:2 scale model with 4150 RPM and 8 points automatic mesh finish normally after 8900 iterations (internal analysis).

                • Re: Jet ski pump solver terminated
                  Amit Katz

                  If you save your file without the CFD results then you can upload it directly to the forums. In general to help you we don't really need your results, just the setup.

                  • Re: Jet ski pump solver terminated
                    David Paulson

                    Patryk,

                    I was not able to open your download file, but from your experience the solver works on a 50% +/- scale model but not on a full scale model at about 5000 RPM.  Possible issues:

                    1.  If the impeller diameter or RPM is not scaled you will not be seeing the same fluid velocities?  A 50 mm impeller scaled to 25 mm will produce much lower pressures and velocities at the same RPM. 

                    2.  You did not state the number of cells in your simulation and the comparison between full scale and 1/2 scale.    I have had similar issues with simulations with 4-5 million cells, until I increased the DRAM in my computer.  More DRAM seemed to fix my problem.

                    3.  4500 iterations seems like a lot.  Solver is struggling for convergence. Did you, or can you, display the solver solution graph?