Correct Answer : Option (B) :   It allows it to varies from one panel to next panel

Explanation : The source strength ‘X’ per unit length be constant over a given panel but allow it to vary from one panel to the next, that if there are total n panel. The source panel strength per unit length is ‘Xn’. Therefore boundary condition is imposed numerically by defining the midpoint of each panel.

Correct Answer : Option (C) :   Sum of the freestream

Explanation : The normal component of the flow velocity at the rth control point is the sum of that due to the free stream and that due to the source panels. The boundary condition stats that this sum must be zero and it is the cruse of the source panel method.

Correct Answer : Option (A) :   True

Explanation : The direction of the outward unit normal vector is positive when directed away from the body and it is carried out in the denominator at a singular point arises on the ith panel because the control point itself can be the contribution to the j=1 panel.