Surface Integral for a point surface:
Problem : Some times using 'Area Weightage Surface Integral' for evaluating a variable value on a point surface created on 'boundary zone', does not give correct results. Resolution : Use Vertex Average Surface Integral Details : Area Weightage Surface Integral value of the Point Surface is taken as the cell center value in/on which the Point Surface lies. So if there is a steep gradient in the value of the variable near the wall, Area Weight age Scheme will not give the expected results. On the other hand, Vertex Average Surface Integral for Point surface calculates the Integral value using value of the variable at all the node value of the cell containing the Point Surface. For the values of variable at each node, an appropriate weightage is given based on the distance of the Point Surface from the corresponding node. Hence it is preferable to use Vertex Average Surface Integral while evaluating a variable on a Point surface created on boundary zone. 

