I am not clear whether to use a Pressure Based Solver or a Density Based Solver.
Thank You in Advance
Dear Samuel, I suggest you Pressure Based Solver because this method is based on body pressure coefficient computation. Gianluca
Since the Pressure based methods are for incompressible or midly compressible flows, I asbased methods are for incompressible or midly compressible flows, I also think you should use Pressure based.
Since the Pressure based methods are for incompressible or midly compressible flows, I asbased methods are for incompressible or midly compressible flows, I also think you should use Pressure based.
Since the Pressure based methods are for incompressible or midly compressible flows, I asbased methods are for incompressible or midly compressible flows, I also think you should use Pressure based.
Since the Pressure based methods are for incompressible or midly compressible flows, I asbased methods are for incompressible or midly compressible flows, I also think you should use Pressure based.
Hello my friend,
this tutorial explains everything
https://confluence.cornell.edu/plugins/servlet/mobile?contentId=323420505#content/view/323420505
It is strongly dependent on your mesh. If you have a fine mesh and already know the position of the shocks you can use a pressure-based solver (activating the energy equation). Otherwise you should switch to density-based solver. Pressure based solver coupled with an inadeguate mesh will smear the shock leading to erroneous wave drag predictions.
From my experience for flow around M=1, OpenFOAM is yields better results than FLUENT.
You can also use pressure based solver, but not the coupled one, instead the segregated SIMPLE algorithm. You can compare the results between density and pressure based solvers.
Density based solver with higher order numerical schemes will work better !
Happy Computing !
Hi Luis,
If you refer ANSYS FLUENT theory guide, you will find this:
"Historically speaking, the pressure-based approach was developed for low-speed incompressible flows,
while the density-based approach was mainly used for high-speed compressible flows. However, recently both methods have been extended and reformulated to solve and operate for a wide range of flow conditions beyond their traditional or original intent.
In both methods the velocity field is obtained from the momentum equations. In the density-based
approach, the continuity equation is used to obtain the density field while the pressure field is determined from the equation of state.
On the other hand, in the pressure-based approach, the pressure field is extracted by solving a pressure
or pressure correction equation which is obtained by manipulating continuity and momentum equations.
Using either method, ANSYS Fluent will solve the governing integral equations for the conservation of
mass and momentum, and (when appropriate) for energy and other scalars such as turbulence and
chemical species."
I suggest:
(I am assuming your grids are refined enough and possess well-posed Boundary conditions)
0. Even though the density changes, there are some flow, still, referred as "incompressible flow".
(Ref. Chapter Computation of Variable Density Flows on Hybrid Unstructured Grids
)1. If there is a strong coupling, or interdependence, between density, energy, momentum, and/or species in your case, you must go with density based solver (irrespective of the Mach number of the flow)
2. But if there is no strong coupling between density, energy, momentum, and/or species in your case then you can go for Pressure Based Coupled Solver. (like combustion, Cp variation due to temperature etc.,)
3. In ANSYS FLUENT, you can have lots of control over your solution in Pressure Based Solver than in density based solver.
(Please also read: www.engr.uconn.edu/~barbertj/CFD%20Training/Fluent/4%20Solver%20Settings.pdf)
4. If you are not convinced yet with the answers/suggestions and if you have time, you can take a simple CD Nozzle with shock case and try all the three solvers viz., PB Coupled solver, PB segregated solver and DBS in fluent and experience it yourself.
(Experimental Investigation of Separated Nozzle Flows by Craig A. Hunter, Journal of Propulsion and Power 20(3):527-532 · May 2004, DOI: 10.2514/1.4612 - - CD Nozzle with/without shock experimental results are available in this paper))
Thanks.
Basically the fluids such as air is considered to be incompressible below 0.3 Mach number and since you are simulating the flow at Mach number 1 , the flow is purely considered as compressible .
Further the pressure based solver is developed for low speed as well as incompressible flows where as for high speed flow as well as compressible flow , density based solver is manily used.
Thus, As your Mach number is 1 you should go with the density based solver .
Basically the fluids such as air is considered to be incompressible below 0.3 Mach number and since you are simulating the flow at Mach number 1 , the flow is purely considered as compressible .
Further the pressure based solver is developed for low speed as well as incompressible flows where as for high speed flow as well as compressible flow , density based solver is manily used.
Thus, As your Mach number is 1 you should go with the density based solver .
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