Learning Forum

[rupatel]

I am trying to plot the X-direction of Full Navier Stokes in CFD post-processing by defining the variable as n(u*du/dx+v*du/dy+w*du/dz)+(1/density)*dp/dx - ((dynamic viscosity/density)*(du/dx. gradient X+du/dy. gradient Y+du/dz . Gradient Z))nI export the results from fluent and defined each term of the Navier stokes equation as a variable according to my model with the help of exported results. And tried to plot this Xdir Navier stokes equation on streamline as well as line. nthis plot is for x-direction, the red line shows results for the fluid domain with the solid cylinder in between. nI have two cases in one case fluid is in wedge shape and in 2nd case same wedge but a solid cylinder in between. nnnresults show that residuals have converged, variable plots are also constant for a certain no of iterations. nSimulation setup-n3D, double-precision, laminar flow(Reynolds no. 0.1), multiphase mixture model, Simple Method nQuesting-nIn the first plot- why is the full Navier-stokes equation is giving peaks near the solid wall. if the fluent has solved the equations with 10^-3 residuals. it means it should not give any residual value. nplease tell me what is the reason behind these peaks.

[rupatel]

Hi Ansys technical support Team,nIn addition to the above question, can someone explain to me the correct way to calculate residuals for the Navier Stokes equation? because when I am calculating residuals by myself in ANSYS Post Processing it's giving values in 10^6 which is not acceptable. and these values (peaks) are near the solid cylinder. Can someone explain to me where I am going wrong. n

[Karthik Remella]

Hello,nTo answer your question, this is how residuals are calculated in Fluent. Please see this link for more information (Fluent Users guide: 36.15.1 - Monitoring Residuals). nhttps://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v211/en/flu_ug/flu_ug_sec_monitor_residuals.html?q=residualnFluent generally uses scaled residuals to judge whether a problem is converged or not. Please see the link for details.nKarthik