Tidal boundary layer Bed friction -> boundary layer Permeates the whole water column Power law approximation for boundary layers Assume a constant mean free surface height h x
Chaplin’s stream function wave theory C u v Finite depth, 2D irrotational wave of permanent form Frame of reference moves with the wave Finite depth wave theory: Incompressible flow Boundary condition Kinematic free surface condition: Bernoulli equation on the free surface: Mean stream flow Wave Disturbance
Tidal flow +wave forces Problems: Depth dependent tide velocity Steady state BEMT Coupling: Doppler effect Alter moving frame of reference
Accelerative forces: The Morison equation c Axial oscillatory inflow: Tangential oscillatory inflow:
The Barltrop Experiments 350mm turbine diameter 200 rpm 0.3m/s 1m/s Wave height 150mm Long waves 0.5Hz Steep waves 1Hz Bending Moments Mx My Towed to simulate tidal flow! Barltrop, N. Et al. (2006) Wave-Current Interactions in Marine Current Turbines. Tidal turbine in a wave tank 2 seperate investigations
The Barltrop Experiments Barltrop, N. Et al. (2007) Investigation into Wave- Current Interactions in Marine Current Turbines. 350mm turbine diameter 200 rpm 0.3m/s 1m/s Wave height 150mm Long waves 0.5Hz Steep waves 1Hz Bending Moments Mx My Barltrop, N. Et al. (2006) Wave-Current Interactions in Marine Current Turbines. 400mm turbine diameter 90rpm 0.7m/s 0.833Hz Varying wave heights 00mm 35mm 84mm 126mm Torque T Axial force Fa Towed to simulate tidal flow! Tidal turbine in a wave tank 2 seperate investigations
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