Torbjørn Utnes

A segregated implicit pressure projection method for incompressible flows

In this paper a segregated, implicit projection method is presented and investigated. Although high-Reynolds, turbulent flow has been a motivating factor, the present study is mainly restricted to the incompressible Navier-Stokes equations. The proposed method is analyzed for properties like stability, accuracy and consistency, aided by some test examples. In addition, two different flow cases are simulated to evaluate the ability and efficiency of the method compared with other results.

A model for sediment re-entrainment and transport in shallow basin flows

Abstract A finite-element vertically-integrated mean flow model and a boundary layer turbulence/sediment model are combined. The resulting model is “first-order” three-dimensional, enabling predictions of sediment re-entrainment, transport and fallout in shallow basins of arbitrary, smooth shape. The model is well behaved and appears to be realistic.

Modelling of Stratified Geophysical Flows over Variable Topography

In the present chapter a short review is given of the mathematical formulation relevant for geophysical flow modelling, and in addition computational examples are shown for some specific flow cases. These examples are described in some detail in order to illustrate useful methods to handle such problems in practice. The emphasis is on more local geophysical flows, including stratified flow over variable topography.

A numerical study on near-bed flow mechanisms around a marine pipeline close to a flat seabed including estimation of bedload sediment transport

Near-bed flow mechanisms of high Reynolds number flows around a marine pipeline close to a flat seabed have been studied using a two-dimensional standard high Reynolds number k- model. The effects of gap to diameter ratio and seabed roughness for a given boundary layer thickness of the inlet flow upstream of the cylinder have been investigated. The vortex shedding mechanisms have been investigated. Mean pressure, mean friction velocity and the resulting mean bedload sediment transport along the bed have been predicted. Overall it appears that for engineering design purposes the present numerical model is suitable for predicting high Reynolds number flows, which are present near the seabed in the real ocean.