مهندسی دریا
Hesamoddin Ravanbakhsh
Abstract
Calculating the forces acting from the fluid to different structures is a field of interest to many researchers. Lift and drag forces are the most important parameters in the hydrofoil issues. Given that the Newtonian Fluid assumption is common in most studies in this field; in this paper, the forces ...
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Calculating the forces acting from the fluid to different structures is a field of interest to many researchers. Lift and drag forces are the most important parameters in the hydrofoil issues. Given that the Newtonian Fluid assumption is common in most studies in this field; in this paper, the forces imposed on a hydrofoil in a laminar non-Newtonian fluid flow have been investigated. The model is Power law for non-Newtonian fluid, and is simulated for three dilatants, Newtonian and pseudo plastic fluid at angles of attack of zero, 5, 10, 15, 20 and 25 degrees, and behavior indexes of 0.5, 1 and 1.5 is considered. Creating Mesh, Processing, and Post-Processing Computing This research is done by three free and open source softwares, G-Mesh, Open FOAM, and Para view. For validation, the lift and drag coefficients in the behavior index 1, that's mean Newtonian fluid, are consistent with similar results. As the angle increases, the dilatant fluid separation phenomenon occurs earlier; also Lowering lift coefficient for this concentrated fluid occurs at a larger angle of attack.
مهندسی دریا
Ahmad Hajivand; Hesamoddin Ravanbakhsh
Abstract
The extensive development and design of multihull ships began in the second half of the twentieth century. Nowadays, many of these ships are built with different designs. However, less numerical and experimental studies have been conducted on their behavior compared to single hull ships. The length and ...
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The extensive development and design of multihull ships began in the second half of the twentieth century. Nowadays, many of these ships are built with different designs. However, less numerical and experimental studies have been conducted on their behavior compared to single hull ships. The length and distance of the two hulls are the factors influencing the wave pattern created around and between the hulls and, consequently wavemaking resistance. In this study, the effect of geometric parameters including length to diameter ratio and body spacing on the hydrodynamic performance of a vessel with a small water plane area surface has been studied using computational fluid dynamics. To investigate the effect of L/D on the wave pattern around the body, towing test is simulated for two models with different ratios in a wide speed range. Furthermore, to evaluate the effect of two-hull distance on the interference of waves between two bodies, two models have been simulated at different distances at different speeds in the computational fluid dynamics environment. Simulations are performed for two different draft. The effect of Froude number, length to diameter ratio and draft on hydrodynamic behavior of the model has also been studied. The pressure, friction and interference resistance of the two bodies are calculated and the wave pattern surrounding the body and between the two bodies is extracted and compared with experimental data, which indicates the reasonable approximation of numerical and laboratory results.