Experimental results are presented on the heat transfer from the bottom of rectangular and trapezoidal trenches streamlined by a turbulent flow. Peculiarities of heat transfer are outlined upon varying both the width and height of rectangular trenches and the width of benches with inclined walls The mean heat transfer at the bench bottom is found to be determined depending on the trench's geometry, either by turbulent diffusional transfer, Nu similar to Re-H(2/3), or turbulent boundary layer, Nu similar to Re-H(0.8). A change from 45 degrees up to 90 degrees in the inclination angle of walls influences heat transfer in a complicated manner: at alpha = 60 degrees the heat transfer is intensified while at alpha = 45 degrees a delay in the transition from laminar to turbulent heat transfer takes place.