Title:	High fidelity simulations in ship propulsion
DNr:	NAISS 2025/5-535
Project Type:	NAISS Medium Compute
Principal Investigator:	Rickard Bensow <rickard.bensow@chalmers.se>
Affiliation:	Chalmers tekniska högskola
Duration:	2025-10-01 – 2026-10-01
Classification:	20302 20306
Keywords:

Abstract

There are several complex problems in ship hydrodynamics that require detailed information on the flow field, thus necessitating the use of scale resolved modelling approaches. The focus area for this project is to advance our capability to perform simulations to assess transient phenomena in marine propulsion systems. This involves dynamic interaction effects between ship, propeller and rudder; separation; cavitation modelling; and underwater radiated noise. Additionally, aerodynamic properties and control for wing sails for ship propulsion will be studied. One main concern relates to predicting the cavitation dynamics, and the consequence in terms of hull pressure pulses and radiated noise. Here, the detailed cavity dynamics in a marine propulsion system needs to be resolved in the simulation and the transient pressure field on the ship structure and in the surrounding fluid is sampled and analysed. Demanding DES or WMLES are needed to capture this dynamics, resolving the internal structure of the developing cavities on the propeller blades as well as the trailing tip vortex cavitation. In some of these processes, also compressibility may need to be considered requiring very small time steps in water. Some activities also relate to advance the modelling of cavitation itself. Cavitation occurs on a large range of scales, from length scales of the propeller diameter down to submillimeter bubbles. New efforts to develop multi scale models coupling these scales will be initiated. Further, assessment techniques for the radiated sound from cavitating flows will be studied. This involves both fundamental investigations and practical methods for ship URN. These methods will be used to study measures to reduce the noise emissions by studying different ship configurations or modes of operation. Some further fundamental work will be done for the turbulence modelling, looking into modelling and resolution demands to correctly capture the flow over lifting surfaces (such as propeller blades and wing sails) and the tip vortex development. Some of these studies are done in two international collaborative efforts looking at modelling requirements (for example wall-modelled LES) to correctly capture the physics for boundary layers over curved surfaces and tip vortex cavitation respectively. The results will further be used in developing active flow control protocols to delay and control stall on wing sails. Common in all problems is that studies aim for simulation in full scale, with Re ranging from around 1e7 to 1e10, thus computationally very demanding. Funding for the research comes from the Swedish Research Council (VR), BluEcho EU project (administered by FORMAS), Chalmers, the Swedish Transportation Agency, and Kongsberg Maritime Sweden AB.