Approaching a practice for transient CFD simulations of vortex flow meters

Licentiate thesis, 2015

The usage of Large-Eddy Simulations (LES) in industrial applications makes it possible to study transient phenomena. The aim of this work is to find a reliable and accurate approach to transient studies of the internal flow field in a vortex flow meter. An initial investigation is made, based on simulation results from a cylinder in cross-flow, which is comparable to a vortex generating rod in a vortex flow meter. The dependency of turbulence models, spatial resolution and wall functions are investigated. Next, a fully synthetic boundary condition is developed to enable efficient and realistic inlet boundary conditions for applications where cyclic boundary conditions are not applicable, e.g. for vortex flow meters. Finally, the outcome from the initial study on the cylinder in cross-flow, and findings during the work with the inlet boundary condition, serves as a base for decision making when a vortex flow meter model is investigated. The results from a LES simulation and two Laser Doppler Velocimetry (LDV) measurements on a vortex flow meter model are compared. The results are evaluated in terms of centreline streamwise mean velocity, variance and vortex shedding frequencies.