[Vino]

Hi,

I would like to clarify how to calculate flux at the interface using Riemann solver (say HLL) for Euler equation(2D). I am able to understand the flux calculation method for 2D-cartesian grids. In case of non-Cartesian gird, can someone tell me how to calculate the flux? Is the formulation correct which I have shown below for Riemann solvers(for any non-Cartesian edge)?

F1= rho*Un
F2=rho*U*Un+p*nx
F3=rho*V*Un+p*ny
F4=rho*E
(U-x velocity,V-y velocity, Un-velocity normal to the edge)

or

Do I need to calculate like this?
Calculate Un and Ut
Then calculate flux using Un & Ut
F1= rho*Un
F2=rho*Un*Un+p
F3=rho*Ut*Un
F4=rho*E

then convert it back to original coordinate as follows

F1=F1
F2=F1*nx-F2*ny
F3=F1*ny+F2*nx
F4=F4

Whether these both are same? Do both hold true for flux calculation using Riemann Solvers?

Thanks in advance.!!!