# transonic calculation

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 May 16, 2003, 11:50 transonic calculation #1 yann Guest   Posts: n/a hi i cannot find in the poor documentation which is the best scemes and solver to use for transonic calculation, where there is supersonic region, sonic region and subsonic region( with possible recirculation) numerically speaking the only good way to deal with that problem is to use a time marching technique because equation are always parabolic following time and whatever the flow (sub, sonic or supersonic). in addition, information propagates trough the domain by means of waves at sound velocity. in subsonic low velocity region this velocity is very high, requiring a prohibitive time step compared to supersonic region. the solver should rescale this sound waves depending on the region (if low (quasi-incompressible) or high (highly compressible) velocity): one means to achieve that is to use matrix preconditionning. secondly, some special care should be brought to the differenciation of the convective term: more upwinding in the supersonic region(hyperbolic) with a flux splitting method such as Roe allowing enough dissipation to capture shock waves. Finally inlet and outlet boundary condition should take into accont the flow caracteristic: at outlet, if it is supersonic the variable should be extrapolated from the interior, while if it is subsonic, pressure should be prescribed... SO , does PHOENICS embodies these capabilities??In this case, which solver , scheme options to take because there is no theory/help about these problems in the *"documentation" thanks for your replies

 May 20, 2003, 10:05 Re: transonic calculation #3 yann Guest   Posts: n/a thanks for the reply... i gonna investigate about the exemples and the different articles... just wanted a quick view if phoenics could deal with a flow containing in the same time, supersonic region with shock -boundary layer interaction, and subsonic region with boundary layer separation (need elliptic function because parabolic solver cannot track recirculation) thanks again. yann

 May 20, 2003, 10:35 Re: transonic calculation #4 cham support Guest   Posts: n/a This seems like the most relevant reference in terms of application area, and since it is published in the PHOENICS Journal, the Q1 input file ought to be included in the journal with the paper. Lee D-B Numerical simulation of oblique shock wave/turbulent boundary layer with wall heat transfer Proceedings, 'Seventh International PHOENICS User Conference', Seville, May 1997. The PHOENICS Journal of Computational Fluid Dynamics and its Applications, Vol. 10, No. 2, pp 179-193, 1997. 97/22

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