Question

When a fluid flows over an object, the "friction drag": __________.A.is the drag due to the shear stress only. B. depends only on the Reynolds number. C. depends only on viscosity and not on the fluid velocity. D. is greater for turbulent flow than for laminar flow

Answer 1

Answer:

D. is greater for turbulent flow than for laminar flow

Explanation:

what is friction drag?

• friction drag is a phenomenon experienced when a body moves through a fluid. A practical example can be seen in the mild warmth we experience rubbing the palm's of one's hand together only in this case we are dealing with a solid body and a fluid (e.g air, water). friction drag is directly proportional to the area of the surface in contact with the fluid and increases as velocity increases. We see a practical example of this when the rate at which one rubs the palms together is fast but we use the word turbulent when we are dealing with fluids. Turbulent flow creates more friction drag than laminar flow( Flow between a smooth body and fluid) due to its greater interaction with the surface of the body
• it is important to know that friction is also called viscous drag or skin drag
• I recommend Richardson and coulson vol 2 textbook, page 149, Chemical enginering fluid mechanics textbook by Ron dardy, page 341 for clearer explanation