Plenary lectures

Application of MPI+OpenMP parallelization for speed up of unsteady flow field simulations in hydraulic turbines

Author:  Denis Chirkov

During the operation of hydraulic turbines there are number of different unsteady flow phenomena that cause undesirable pressure pulsations in the flow passage. It is important to predict the frequency and amplitude of these pulsations at the stage of turbine design. In the report the unsteady flow in hydraulic turbine is numerically simulated in frames of RANS equations, closed by Kim-Cnen ke or SST turbulence model. The system of equations is discretized by implicit finite volume method, using the approach of artificial compressibility. The use of block-structured meshes in the whole computational domain allows us to efficiently parallelize the computations using both MPI and OpenMP. Presented are the results of simulation of two unsteady flow phenomena. First is the rotation of helical vortex rope in the draft tube. Second is the von Karman vortices, shedding from the trailing edges of the runner blades. Typically, the use of hybrid MPI+OpenMP parallelization reduces computational time to a factor of about 20, allowing to apply the code for daily industrial computations.