## Abstract

This study presents a detailed comparison between the k-. e(open) and k-. τ turbulence models. It is demonstrated that the numerical accuracy of the k-. e(open) turbulence model can be improved in geophysical and environmental high Reynolds number boundary layer flows. This is achieved by transforming the k-. e(open) model to the k-. τ model, so that both models use the same physical parametrisation. The models therefore only differ in numerical aspects. A comparison between the two models is carried out using four idealised one-dimensional vertical (1DV) test cases. The advantage of a 1DV model is that it is feasible to carry out convergence tests with grids containing 5 to several thousands of vertical layers. It is shown hat the k-. τ model is more accurate than the k-. e(open) model in stratified and non-stratified boundary layer flows for grid resolutions between 10 and 100 layers. The k-. τ model also shows a more monotonous convergence behaviour than the k-. e(open) model. The price for the improved accuracy is about 20% more computational time for the k-. τ model, which is due to additional terms in the model equations. The improved performance of the k-. τ model is explained by the linearity of τ in the boundary layer and the better defined boundary condition.

Original language | English |
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Pages (from-to) | 129-142 |

Number of pages | 14 |

Journal | Ocean Modelling |

Volume | 104 |

DOIs | |

Publication status | Published - 1 Aug 2016 |

## Keywords

- Boundary layers
- K-e(open) model
- K-τ model
- Numerical accuracy
- Turbulence modelling