Hi Zach, For characteristic BCs I believe the syntax in 2D is:
[soln-bcs-$name] type = char-riem-inv rho = ... u = ... v = ... p = ... Whether you go non-dimensional or not is largely down to personal preference - for me it simplifies things. I would certainly try reducing the time step - however I am pretty certain you will also need to run on a finer mesh than the one you attached here initially. Cheers Peter On 11 Jun 2014, at 01:51, Zach Davis <[email protected]<mailto:[email protected]>> wrote: 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]<mailto:[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]<mailto:[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]<mailto:[email protected]>. To post to this group, send email to [email protected]<mailto:[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> -- 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 an email to [email protected]. Visit this group at http://groups.google.com/group/pyfrmailinglist. For more options, visit https://groups.google.com/d/optout.
