variavel0=<b>Sonia Magalhães dos Santos</b> - vnsantos@mikrus.com.br FURG
<b>Jorge Alberto Almeida</b> - dfsjaa@furg.br FURG
<b>Ivoni Carlos Acunha Jr.</b> - dfsica@furg.br FURG
<b>Luciano Vaghetti de Oliveira</b> - lvaghetti@vetorialnet.com.br FURG
<b>Abstract.</b> The microalgae velocity field is studied in a culture tank in order to obtain the settlings tax and the movement, as well as the air circulation forms for best survival. The circular shape acrylic tank contains air inlets on bottom side (six peripheral and one in the center), and the air flow is measured by a flow meter in order to inject equal volumes of air. A laser light beam is transformed in a small thickness plane after passing through a cylindrical lens, and the moving microalgae are illuminated by the incident laser plan in a tank diameter. A CCD video camera is located perpendicularly to the plan of laser. The successive images obtained provide a determination of the flow field which is obtained by the cross correlation method. The region enclosing the place in which the velocity is obtained is selected from the first image, and then the same particles configuration is searched from the second image where is the maximum correlation coefficient. Five laser planes were constructed between two adjacent air inlets delayed by 15o. The objective of the study is to analyse the 3-D behavior of the microalgae movement by applying the mass conservation equation between two adjacent planes.
<b>Keywords.</b> multiphase flow, 3D flow, velocimetry by images particles.