Development of turbulent flow around a triangular obstacle, vortex generation and resulting effect on neighboring turbulent boundary layer over a flat plat, is studied. Vortex shedding controlled in size by changing side length and relevant angle of the obstacle. The distance of triangular obstacle from the flat plate changed, beginning from a point sticked to the plate and then moving away from the plate, up to a point outside the boundary layer. As a result, one or two vortices, a jet and a stagnation point form and each contribute on changing the heat transfer from neighboring flat plate. One effects on causing in reduction and the other results in enhancement of heat transfer. Most effective part of flow is the second vortex downstream to the obstacle. Its contribution to total enhancement is more than 80% and has leading affect to enhancement. Overall effect in this technique is to increase the heat transfer by more than 60% if compared to a single flat plate for similar flow field. Effect of vortices is major both locally and over the whole range of disturbed area.

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