A white-light speckle technique for measurement of flow velocities is described. The speckle patterns are formed by incoherent light at the image plane of the fluid illuminated section. The convection flow generated in a rectangular cell filled with silicone oil is studied with this technique. The flow velocities are obtained as the result of a point-by-point analysis. Alternatively, an overall picture of their spatial distribution is obtained by means of a whole-field filtering technique. The accuracy of the two methods of analysis is studied.
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