Question

The schadowgraph flow visualization technique depends on

• A. the variation of the value of density in the flow
• B. the first derivative of density with respect to spatial coordinate
• C. the second derivative of density with respect to spatial coordinate
• D. the third derivative of density with respect to spatial coordinate

Hint:

Shadowgraph is particularly useful in identifying shock waves and expansion fans in aerodynamics, as these phenomena involve rapid changes in the density field.

Answer 1

The Correct Option is C

Step 1: Understand Shadowgraph Technique. The shadowgraph technique in flow visualization is used to visualize changes in fluid density, particularly effective in supersonic flows. It captures the patterns formed by light passing through density variations in the fluid.
Step 2: Relate to Density Derivatives. This technique depends specifically on the second derivatives of density with respect to spatial coordinates, which affect the curvature of light rays passing through the fluid due to changes in the refractive index.