Numerical CFD study on the frictional drag reduction using air lubrication - PhDData

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Numerical CFD study on the frictional drag reduction using air lubrication

The thesis was published by Ottosen, Jacob Bjørn Helmers, in January 2022, Aalborg University.

Abstract:

In this study a series of multi-phase Large Eddy Simulations with the Volume Of Fluid approach are made to analyse the use of air lubrication to reduce the drag on a ship by injecting air bubbles underneath the hull. The multi-phase simulations are initialised with a turbulent velocity profile obtained from simulations with a single-phase computational model, which is validated against theory, by comparing the turbulent boundary layer with the law of the wall. In the multi-phase simulations, the air volume fraction is varied from 14 – 50%. In the case with an air volume fraction of 14% a reduction in wall shear stress of 20 – 40% is seen. In the other cases with an air volume fraction from 27 – 50% a reduction of 40 – 60% in the wall shear stress is seen compared to the values using the single-phase model.



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