3 Replies Latest reply on Oct 28, 2014 5:58 PM by Jared Conway

    error with flow simulation in calculus

    Mohamed Samy
    Mohamed Samy Oct 26, 2014 6:50 PM

      Hi

      I'm using flow simulation in solidworks on sphere to get drag coefficient and known that the drag coefficient = 0.44 when Reynold number = 10,000 to 10^5
      So I draw sphere with radius of 0.025 m and made speed = 3.1 m/s then
      Re =V*D/v where v = kinematic viscosity = 1.5111 * 10^-5
      Re = 10,250

       

      I made global goal force(x) and velocity(x) and i made equation goal cd = 2*force(x)/(1.204*3.141592*0.025^2*velocity(x)^2)

      and after running cd not equal 0.44 it equals 0.17 !!


      is it error in program or in my calculations or in what ?!!

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        • Re: error with flow simulation in calculus
          Jared Conway
          Jared Conway Oct 26, 2014 11:19 PM (in response to Mohamed Samy)

          have not validated your calcs/equation as I assume you have checked those thoroughly so here are some questions:

           

          have you checked a surface goal instead of just global goal?

          do pressure and velocity/pressure distributions look correct?

          has the solution converged completely?

          have you checked drag force in addition to the Cd?

          what does your mesh look like?

          how big is your comp domain?

          have you tried a transient analysis?

          have you looked at the tutorial/validation problem in the documentation for this exact setup?

            • Re: error with flow simulation in calculus
              Mohamed Samy
              Mohamed Samy Oct 27, 2014 3:55 PM (in response to Jared Conway)

              "have you checked a surface goal instead of just global goal?"No, I didn't
              you mean surface goal instead of global goal or use both of them together and get average ?? to try it

               

              "do pressure and velocity/pressure distributions look correct?"Yes, i think velocity distributions looks correct see the image

              p.png

              v.png

               

              "how big is your comp domain?"I let them in this shape after the program put there size

               

              "have you tried a transient analysis?"No and i don't know what is "transient analysis" means

               

              "has the solution converged completely?" You mean running of flow simulation !! if right yes it finished running

               

              "have you looked at the tutorial/validation problem in the documentation for this exact setup?" No and i can't find them

               

              I don't know what other question mean

               

              I'm sorry, I don't know lots of things about flow simulation but i didn't found tutorials in youtube that can teach me flow simulation

               

              Jared Conway