Measurement of pressure field around a NACA0018 airfoil from PIV velocity data

Rudder hydrodynamics behind a propeller rotating ahead and astern

“…Therefore, the medium ∆t = 2.315 × 10 −4 s is adopted from the perspective of balancing the accuracy and the efficiency of numerical simulations. By changing the inflow velocity while keeping n = 12 rps fixed, exactly as experimental settings in Fujisawa [12], RANS simulations are conducted for open water characteristics of KP505 propeller. The comparison with the experimental data in Figure 4 shows that deviations between CFD and EFD results for K T and K Q are within 5% for J = 0.5 ∼ 0.7, while η show larger deviations for higher J. Simulation results for lighter loading conditions are not as accurate as heavier ones, and one possible reason is that the propeller is assumed to experience fully developed turbulence flows, so transitions from laminar to turbulent states existing in model tests are not captured accurately.…”

Hydrodynamic stress maps on the surface of a flexible fin-like foil

“…An alternative approach to calculate the total hydrodynamic force relies on a momentum balance inside a control volume and was also employed in the context of flapping fin-like structures [25,26,34,[53][54][55][56][57][58][59][60][61][62][63][64][65]. A non-invasive method to determine the three-dimensional pressure field inside an unsteady flow domain consists in solving the Navier-Stokes equation, in either one of the two following forms: (1) the pressure gradient is expressed in terms of spatial and temporal derivatives of the velocity field and engaged in a direct spatial integration to compute the pressure values everywhere in the domain [17,[65][66][67][68][69][70][71][72][73][74][75][76][77][78][79], or (2) the Laplacian of the pres-sure is obtained by taking the divergence of the latter pressure gradient formulation, and this so-called Poisson equation is solved numerically [69,72,73,[79][80][81][82][83][84][85]…”