| Coming Soon Some results regarding comparison of usual flat bottom hull and concave stepped hull can be driven form theory Sedov L.I , VLM methods and CFD simulation . 1.Below is a simple cfd simulation of test common flat hull( No V, flat rocker till 70cm from tail ) in stationary movement without side drift( symmetry case) , and absolutely flat water :)) ( no chop) trim angle= 3degrees, мудщсшен V=10 m/s, max width of wetted surface = 62 cm , estimated Efficiency Fy/Fx =10.25 Mesh in virtual towing tank uses trim cells mesher with special remesh around body and free surface  below is the free surface scene after 2420 itterartions of cfd solvers  Cp ( pressure coefficient distribution )   2. Second case : only step is added ( pink) compared with the 1) flat case specially choosen step with camber (concave)   almost the same mesh in Virtual towing tank trimed cells Intersesting to compare the efficiency of the slightly changed by cambered step board at the same speed V=10 m/s to be the same lift Fy and almost the same center of pressure . Trim angle is 1.5 degree Cp pressure distribution on the bottom with special cambered step :   with higher efficiency 13.5 ( trim angle 1.5 degree ), more information is to be added soon But now it can be noticed that it is possible to achieve higher efficiency Fy/Fx 13.5 compared to 10.25 ( less drag with the same Lift ) in the case of special height step with camber . Due to camber addditional lift is produced and it is less wetted area needed and less trim angle to achive the same Lift with the same width . As a result 1) aspect ratio or wetted surface is higher . |