CFD & FEA: Introduction | CFD (details) | FEA (details)

Flow Simulation Services: CFD – Hydrodynamic Engineering. Some projects, such as, the removal of cavitation generated by a ship rudder include the use of both inviscid and viscous CFD codes.
Inviscid flow projects include:

• Propeller modelling
• Rudder modelling
• Cavitation modelling

Viscous flow projects include:

• Rudder and propeller interaction with or without the ship afterbody
• Smoke and ventilation studies
• Ship response in adverse sea conditions
• Explicit modelling of cavitation
• Wake field calculation for inviscid flow projects
• Pressure field calculation to provide boundary conditions for FEA

Inviscid Flow Modelling on a Propeller: BEM represents a straight forward and rapid method for determining the characteristics of a propeller.

• Transient analysis
• Rotational symmetry in the model
• From the time domain to the frequency domain

Steady State Rudder Modelling using RANS: This is a straight forward analysis with the propeller modelled by an actuator disk. From the calculation we obtain:

• The drag, lift and torque on the rudder
• The pressure field for export to FEA as a boundary condition
• An understanding of the flow field around the rudder
• A clear warning about the risk of cavitation generated by the rudder
• The wake field for use in the BEM code

Cavitation Modelling on Rudders and Propellers: Cavitation modelling for rudders involves making subtle design changes to remove the risk of cavitation. The aim is to design a rudder that does not generate cavitation. At ibmv we run the BEM code in:

• Steady state mode
• Wake field taken from the RANS code
• Calculate σ_y
• Co-ordinate adjustments made either automatically or interactively to the rudder to ensure σ_y>0.

Explicit Modelling of Propeller Cavitation: Transient RANS calculation to accurately capture propeller hub and blade cavitation. The example shown includes periodic hub cavitation and the variation of cavitation wth depth. The geometry is a tanker propeller.