[dinhanh]

Hi,
I am making the code based on the Yee's symmetric TVD scheme. The finite difference method that I used. I got the difficulty on implimentation of the minmod limiter function at the point 1/2 and point ni-1 (Here the grid is 2D: i=1,ni and j=1,nj). The minmod limiter is expressed as below in Eq(2.41)

The problem is that for finite difference method, the value at point out of domain is unknow. So for value of Qa(1/2) and Qa(ni-1/2) in Eq(2.41) the value od alpha(-1/2) and alpha(ni+1/2) is unknow.

So how can I calculate the minmod limiter at point 1/2 and point ni-1/2? Thank in advance!