Question

JUTUI dull secuull. Wily is a large n u prea 13. Assuming that we need to understand the flow pattern around a scaled-down building model using a wind tunnel. What flow visualization methods can you suggest for this problem? What is the limitation of your flow visualization method? cita

Answer 1

One can use Schlieren imagery or shadowgraph (if only a rough estimate or "feel" of the flow pattern is required). However none of the methods provide a quantitative estimate to the flow pattern (Schlieren provides a contrast based estimate which tells about the rate of change in density, instead of the density change).

A far superior method is PIV or particle image velocimetry. It consists of impregnating the flow field with small seeding particles, and the flow is made to pass with a thin laser sheet, created by fast pulsating lasers.

When the seeding particles interact with the laser, they scatter light. This scattered light is then captured via cameras and is then cross referenced cell by cell in order to generate the flow field.

Disadvantages: Highly complicated and expensive to implement and thus should be used only if very accurate data is needed. Also it is a laser based technique which means the data can be acquired only after the laser fires again, i.e in a delay of the order of certain microseconds.

For less accurate data smoke visualization and other qualitative methods can be employed