Current Capabilities of DES and LES for Submarines at Straight Course

Abstract

The flow around an axisymmetric hull, with and without appendages, is investigated using large eddy simulation (LES), detached eddy simulation (DES), and Reynolds averaged Navier Stokes (RANS) models. The main objectives of the study is to investigate the effect of the different simulation methods and to demonstrate the feasibility of using DES and LES on relatively coarse grids for submarine flows, but also to discuss some generic features of submarine hydrodynamics. For this purpose the DARPA Suboff configurations AFF1 (bare hull) and AFF8 (fully appended model) are used. The AFF1 case is interesting because it is highly demanding, in particular for LES and DES, due to the long midship section on which the boundary layer is developed. The AFF8 case represents the complex flow around a fully appended submarine with sail and aft rudders. An actuator disc model is used to emulate some of the effects of the propulsor for one of the AFF8 cases studied. Results for the AFF8 model are thus presented for both "towed" and "self-propelled" conditions, where as for the bare hull, only a "towed" condition is considered. For the AFF1 and the "towed" AFF8 cases experimental data are available for comparison, and the results from both configurations show that all methods give good results for first-order statistical moments although LES gives a better representation of structures and second-order statistical moments in the complex flow in the AFF8 case.

Large Flow Separations around a Generic Submarine in Static Drift Motion Resolved by Various Turbulence Closure Models

“…The major contribution of this work is the overall quality of solutions brought by the combined use of adaptive mesh refinement along with the DES or IDDES-based turbulence closure models. Comparing the solutions reported here with the otherwise faster but less accurate RANS methods [15,20], or with the more expensive LES-based methods [23,35,66] one may notice not only the efficiency, but also the accuracy of the method proposed here.…”

“…Most of the studies on the DARPA Suboff model are only based on the axisymmetric hulls appended with pairs of rudders and stabilizer fins that are small compared to the length of the hull, [14,[34][35][36]. Captive model tests provide information on flow physics but have certain limitations imposed by the equipment that constrain its usefulness.…”

Verification and Validation: the Path to Predictive Scale-Resolving Simulations of Turbulence

“…Scale-resolving simulation (SRS) models are nowadays widely applied in computation of turbulent flow problems of practical interest, e.g., vehicle aerodynamics and hydrodynamics [1,2,3,4,5,6,7], offshore engineering [8,9,10,11,12,13], propeller design [14,15,16,17,18,19], material mixing [20,21,22,23,24,25], and combustion [26,27,28,29,30,31]. These formulations are characterized by their ability to resolve a fraction of or all turbulence scales present in a flow.…”

Computational study on the effect of the shape of ducts on the performance of the submarine propeller

“…The simulated dynamic cavitation 6 calculation is based on the LES model. [7][8][9][10][11][12] This model setup uses a single-fluid, two-phase mixture description of the cavitation combined with a finite rate mass transfer model. 13 The computational output is for a full submarine propeller using Ffowcs Williams-Hawkings (FW-H) equations 14,15 to compute with unsteady flow.…”