scholarly journals Assessment of Statistical and Hybrid LES Turbulence Closures for Surface Combatant DTMB5415 at 20° Static Drift Condition

Author(s):  
Michel Visonneau ◽  
Emmanuel Guilmineau ◽  
Jeroen Wackers ◽  
GanBo Deng ◽  
Patrick Queutey

This paper provides detailed validation of the complex free-surface flow around the surface combatant DTMB5415 at 20° static drift conditions. Particular emphasis is being placed on the onset and progression of the various vortical structures created at the sonar dome, at the free-surface and around bilge keels in conditions where free-surface breaking may occur. A detailed analysis of this complex free-surface flow is conducted on grids which are dynamically refined to capture the vortical structures. Local comparisons with recent experiments performed at the Iowa Institute of Hydraulic Research (IIHR) during a joint NATO-AVT (Advanced Vehicle Technologies) collaboration are used to perform detailed flow analysis and draw some conclusions about the actual potentialities of advanced Computation Fluid Dynamics (CFD) method in terms of physical and numerical modeling.

Author(s):  
Jun Imasato ◽  
Yuzuru Sakai

In this study a new computational algorithm to enforce incompressibility in free surface flow analysis using Smoothed Particle Hydrodynamics (SPH) is presented. The method uses two steps. The first step is a fractional step for solving velocity field forward in time without incompressibility. Then the second step is computed to compensate the pressure Poisson equation using the mass constant equation in a particle field. This method is composed of the above two steps and is similar to SMAC (Simplified Marker and Cell) method commonly used in CFD. However in SPH simulation, the introduction of incompressibility of fluid is easily realized using the particle density concept and the boundary of free surface of fluid is also controlled conveniently by the concept. In this study the algorithm is applied to sloshing problems of vessels with fluid. The numerical results using this algorithm show good results in the behaviors of free surface flow and the pressure evaluations at the wall of the vessels.


2014 ◽  
Vol 2014.24 (0) ◽  
pp. 186-189
Author(s):  
Sou Hirama ◽  
Yasuyuki Nishi ◽  
Terumi Inagaki ◽  
Yanrong Li ◽  
Norio Kikuchi

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