1. A laminar flow over a cylinder has a less negative value for the minimum pressure coefficient than an inviscid flow

Question

2. The drag due to friction is higher than the drag due to pressure

Select the answer that matches

Only statement 1 is true

Only statement 2 is true

Both statement 1 and statement 2 are true

Neither statement 1 nor statement 2 are true

Answer 1

To analyze the truthfulness of the statements given, let's break them down one by one.

1. A laminar flow over a cylinder has a less negative value for the minimum pressure coefficient than an inviscid flow.

   • In laminar flow over a cylinder, the flow tends to separate earlier compared to inviscid flow. This separation leads to a tripping of the flow, which can cause an increase in pressure in the wake region, resulting in a less negative minimum pressure coefficient compared to inviscid flow. Therefore, this statement is true.

2. The drag due to friction is higher than the drag due to pressure.

   • In typical cases for an object like a cylinder in a flow, especially at higher Reynolds numbers, pressure drag tends to dominate due to flow separation and the pressure difference across the body. However, in low Reynolds number flows (laminar flow conditions), friction drag can be significant. Overall, it is often found that for an object like a cylinder at moderate to high Reynolds numbers, pressure drag becomes more substantial than friction drag. Thus, this statement is often false.

Considering the analyses above:

• Statement 1 is true.
• Statement 2 is false.

Thus, the answer that matches is: Only statement 1 is true.