A numerical simulation of wavy core flow was carried out previously. They calculated the interfacial wave shape for laminar flow. In our present simulation, the shear stress transport turbulence model is used to solve the turbulent kinetic energy and dissipation rate equations and a splitting method is used to solve Navier-Stokes equations for the wave shape, pressure gradient and the profiles of velocity and pressure in turbulent wavy core flows. The wavelength decreases with Reynolds number R and with the volume ratio eta. The pressure gradient increases with Reynolds number R and with the volume ratio eta. High pressures are generated at a stagnation point leading to wave steepening, while low pressures are generated at a reattachment point. The computed wave shapes and frictional losses are in satisfactory agreement with experiments and greatly improve on previous results. (C) 2002 Published by Elsevier Science Ltd.