The accuracy of the flow depending on the direction
 

Dear All

Hi I just wonder simple question about the prediction accuracy of the CFD

When the flow direction is streamwise, why prediction of vertical velocity accuracy is lower than streamwise velocity???

is that because of main stream direction???

but still what is the origin reason for this??

Any clue about this?

Best Regards

First, the order of accuracy is a property of the discretization, not of the flow direction.
I suggest to do a simple exercise: FD discretization of the linear 2D convection equation with the upwind scheme and first order Euler. Then look at the modified equation and see what happen in case you have u and v of different ratio.

On the other hand, FVM can be built to have a real multidimensional approach, with less dependence on the flow direction.