Experimental investigation of the log-law for an adverse pressure gradient turbulent boundary layer flow at Reθ up to 10000

We present an experimental investigation of a turbulent boundary layer flow at a significant adverse pressure gradient at Reynolds number Re-theta up to 10000 using large field PIV. The testcase is designed to start from a zero pressure gradient flow at Re-theta approximate to 8000 with a distinct log-law region following a slowly rising adverse pressure gradient. This allows to reveal a breakdown of the log-law under the effect of the adverse pressure gradient. The region described by the log law is progressively reduced in terms of y(+) and then joins into a modified log-law which gives a good fit to the data up to at least y/delta(99) approximate to 0.2.