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

Adrian Lungu

doi:10.3390/jmse10020198

Abstract

A thorough numerical introspection for assessing the particular issues of large flow separations around a submersible hull by using various turbulence models is described. The generic Defense Advanced Research Projects Agency (DARPA hereafter) Suboff hull is considered in the present study. Detailed descriptions of the mathematics behind the hybrid Shear Stress Transport (SST), Detached Eddy Simulation (DES) and the Improved Delayed Detached Eddy Simulation (IDDES) are given. The ISIS solver of the FineTM/Marine package is used to solve the flow problems. An adaptive mesh refinement is employed for resolving the flow inside the areas hosting significant flow gradients. Two sets of computations are analyzed: one refers to the straight-ahead course, whereas the other is focused on the static drift motions. Four angles of incident flow and three different incoming flow velocities are proposed for clarifying the details of the flow separation. Extensive grid convergence tests are performed for both working regimes and for all the meshes used in the present investigation. Extended verification and validation (V&V hereafter) of the numerical approach is performed through extensive comparisons with the experimental data. Global hydrodynamic performance of the hull as well as the local flow features are discussed in detail. The study is concluded by a series of final remarks aimed at providing useful information for further similar investigations.

Highlights

Academic Editor: Zaojian ZouThe accurate estimation of forces and moments is crucially important in predicting the response of a hull that moves in a direction which does not coincide with the flow direction
The proportionality factor of Menter was set as λ = 1, which is recommended for boundary layer flows
Since the main subject of the present research is related to the DARPA Suboff hull hydrodynamic performances in a static drift motion, an initial validation might be appropriately required for the straight run working condition

Summary

Introduction

Academic Editor: Zaojian ZouThe accurate estimation of forces and moments is crucially important in predicting the response of a hull that moves in a direction which does not coincide with the flow direction. At low angles of attack (drift), the flow does not usually separate, and inertial forces dominate. For such cases, good agreement with experimental data can be achieved by using either potential flow or Euler codes. The viscous effects are important, and it becomes essential to use a Navier–Stokes code to correctly model the physics and obtain good agreement with experimental data [1]. A complete understanding of Reynolds number effects is essential for extrapolating the model-based solutions to full scale. A reliable prediction of the overall hydrodynamic performances should comprise a good understanding of the scale effects at full-scale Reynolds numbers, as previously proved for propellers by the author [2]. The preponderance of experimental data available for undersea vehicles is limited to model-scale

Objectives

Results

Conclusion