[amp_mcq option1=”d > m > e” option2=”d > e > m” option3=”e > m > d” option4=”e > d > m” correct=”option3″]
The correct answer is: C. e > m > d
Displacement thickness is a measure of how much the boundary layer displaces the freestream flow. Momentum thickness is a measure of how much the boundary layer reduces the momentum of the freestream flow. Energy thickness is a measure of how much the boundary layer reduces the energy of the freestream flow.
Since the boundary layer reduces the momentum and energy of the freestream flow, the displacement thickness, momentum thickness, and energy thickness must be greater than or equal to zero.
The displacement thickness is the smallest of the three thicknesses, since it only measures the displacement of the freestream flow. The momentum thickness is greater than the displacement thickness, since it also measures the reduction in momentum of the freestream flow. The energy thickness is the greatest of the three thicknesses, since it also measures the reduction in energy of the freestream flow.
Therefore, the correct relationship among displacement thickness, momentum thickness, and energy thickness is:
e > m > d