What is the reduction of drag by installing the small cylinder?

48%

55%

75%

95%

Correct Answer : 48%

Explanation : A 48% drag reduction of a cylinder by installing a much smaller cylinder in the upstream direction of flow. The shear layer coming from the smaller cylinder changes the pressure distribution around the layer cylinder in such a way that the drag is dramatically altered.

Recently Updated in Aerodynamics Questions

Why source strength 'X' per unit length is constant over a given panel?

It remains in the same panel

It allows it to varies from one panel to next panel

The length will be changes from panel to panel

It does not allow it to varies from one panel to next panel

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.

What is the normal component of the flow velocity at the rth control point?

Sum of source line

Sum of the sink line

Sum of the freestream

Sum of the source and sink line

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.

Is vector (v) is positive when directed away from the body?

True

False

Can Not Say

None of the above

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.