Hi Peter, Thanks for getting to this for me. Would you be able to describe for me the requisite input parameters for these characteristic boundary conditions? It sounds like I may prefer to utilize those. When using the non-dimensional form, are you indicating it is easier for the solver or from a user-perspective. I don’t have a preference whether the variables are dimensionalized prior to the simulation running or during post-processing; though, at some point along the way I will need to do it. Although, I guess I prefer to see the output already in metrics to which I’m accustomed, so maybe I lied in my previous statement. I’ll try reducing the time step further as well to cover all of my bases.
Best Regards, Zach On Jun 10, 2014, at 5:23 PM, Vincent, Peter E <[email protected]> wrote: > Hi Zach, > > Thanks for your interest in PyFR. A few comments: > > 1.) The initial condition should be set according to: > > [soln-ics] > rho = (psp*32.174)/(r*tsp) ; Freestream Density (lbm/ft^3) > u = 558.166 ; X Component Velocity (ft/s) > v = 9.743 ; Y Component Velocity (ft/s) > w = 0.0 > p = r*tsp*rey*mu/usp ; Freestream Pressure (lbf/ft^2) > > from within your .ini file. > > 2.) The following may be the cause of the solution blowup: > > - The mesh is very coarse for a p = 3 run, and hence you are likely > dramatically under resolving the flow > - Your time step may be too big, and hence violating the CFL limit (PyFR is > explicit in time) > > 3.) Other comments: > > - It may be easier to do everything in non-dimensional form (i.e. chord of 1, > inflow speed of 1, free stream density of 1, then set Mach number with the > free stream pressure and set the Reynolds number with the viscosity. > - You may want to try using our new characteristic BCs (type=char-riem-inv) > for this case (available in v0.2.1). They are not currently documented, but > require specification of the full free stream state. > > Hope this is of some help. Others may have more detailed comments. > > Cheers > > Peter > > On 11 Jun 2014, at 00:21, Zach Davis <[email protected]> wrote: > >> All, >> >> I've posted this enquiry to both Freddie and Peter already, but perhaps >> others would be able to contribute or be interested in its resolution. I've >> made a couple initial attempts to try to setup and run a simulation around a >> 2D NACA 0012 series airfoil with conditions set at mach = 0.5, aoa = 1 deg, >> rey = 5000 (ref length = 1ft) at SLS (or tsp = 518.688 deg R). I've >> generated a few meshes of varying mesh density. The latest of which I've >> shared here is my first attempt at generating a very coarse curvilinear mesh >> via Gmsh. After inspecting the initial flow solution, it appears that the >> fields for pressure, density, and velocity are set according to those >> prescribed by the boundary conditions. It appears that the solution >> diverges very quickly after beginning the run, and I'm trying to better >> understand why this occurs as I attempt to become more familiar with PyFR >> and its options. >> >> Best Regards, >> >> >> Zach Davis >> >> enc >> >> -- >> You received this message because you are subscribed to the Google Groups >> "PyFR Mailing List" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To post to this group, send email to [email protected]. >> Visit this group at http://groups.google.com/group/pyfrmailinglist. >> For more options, visit https://groups.google.com/d/optout. >> <naca_0012_coarse.msh><naca_0012_2d.ini> >
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