Two subsequent presentations on the 13th UnTRIM Workshop 2016 with the same title* Efficient river modelling applying subgrid technology (UnTRIM2)*, the first part concerning *concept and grids,* presented by Regina Patzwahl, and the second part concerning *results,* presented by Jacek A. Jankowski. Continue reading

# Tag Archives: fluvial flows

# On the representation of bottom shear stress in z-layer models

*F. Platzek, G.S. Stelling, J.A. Jankowski, R. Patzwahl*

**Abstract.** Bottom friction plays an important role in modelling river flows. In three-dimensional (3D) models, the vertical discretization is commonly based on σ-layers or z-layers. In this paper we focus on a well-known problem encountered when applying z-layers: local truncation errors in the computation of bottom shear stress and near-bed turbulence along a sloping bottom as e.g. in the case of 3D river simulations. This problem stems from the ‘staircase’ representation of the bottom and results in difficulties in the computation of morphological changes. Continue reading

# UnTRIM applications for fluvial flows

*Jacek A. Jankowski. *UnTRIM applications for fluvial flows, 1st UnTRIM Workshop, Verona, 7-9 June 2004.

Attracted by the proven and excellent mathematical properties of the scheme and the ongoing OpenMP parallelisation of the UnTRIM code, BAW Karlsruhe has initiated an internal investigation to assess the feasibility of the freshly developed code for the engineering applications concerning river flows. Continue reading