URANS Study of Air-Layer Drag Reduction in a High- Reynolds-Number Flat-Plate Turbulent Boundary Layer

The air layer formation in a high Reynolds-number flat plate turbulent boundary layer is simulated using a two-phase sharp interface Cartesian grid solver. The interface is tracked by a coupled level set and volume-of-fluid method (CLSVOF) and turbulence is modeled by a Spalart-Allmaras (SA) turbulence model with a wall function (WF) approach. The air layer along the entire test plate is successfully achieved and the drag reduction is approximately 100%, which agrees very well with the experimental findings. With reduced air flow rate, bubble drag reduction (BDR) is also observed; the computational results also qualitatively match the experiments. The transitional region from BDR to ALDR is also observed in the present simulation. However, the critical air flow rate to form the ALDR is lower in the simulations than in the experiments. Several possible reasons are likely accounting for the low critical air flow rate in the simulations, such as SA-WF turbulence model, three-dimensional instability and surface tension effects. The critical air flow rate does not change much with grid refinement.

[1]  J. Dacles-Mariani,et al.  Numerical/experimental study of a wingtip vortex in the near field , 1995 .

[2]  F. Stern,et al.  A coupled level set and volume-of-fluid method for sharp interface simulation of plunging breaking waves , 2009 .

[3]  Robert D. Falgout,et al.  The Design and Implementation of hypre, a Library of Parallel High Performance Preconditioners , 2006 .

[4]  Frederick Stern,et al.  Sharp interface immersed-boundary/level-set method for wave-body interactions , 2009, J. Comput. Phys..

[5]  S. Osher,et al.  A level set approach for computing solutions to incompressible two-phase flow , 1994 .

[6]  Ebrahim Shirani,et al.  Turbulence Models for Flows with Free Surfaces and Interfaces , 2006 .

[7]  Djamel Lakehal,et al.  Multi-physics treatment in the vicinity of arbitrarily deformable gas-liquid interfaces , 2007, J. Comput. Phys..

[8]  Frederick Stern,et al.  Scalability studies and large grid computations for surface combatant using CFDShip-Iowa , 2011, The international journal of high performance computing applications.

[9]  Nan-Suey Liu,et al.  APPLICATION OF GENERALIZED WALL FUNCTION FOR COMPLEX TURBULENT FLOWS , 2003 .

[10]  Nan-Suey Liu,et al.  Application of generalized wall function for complex turbulent flows , 2003 .

[11]  D. T. Walker,et al.  Reynolds-averaged equations for free-surface flows with application to high-Froude-number jet spreading , 2000, Journal of Fluid Mechanics.

[12]  David R. Dowling,et al.  Bubble friction drag reduction in a high-Reynolds-number flat-plate turbulent boundary layer , 2006, Journal of Fluid Mechanics.

[13]  Eduard Amromin,et al.  Partial Cavitation as Drag Reduction Technique and Problem of Active Flow Control , 2003 .

[14]  David R. Dowling,et al.  Bubble-induced skin-friction drag reduction and the abrupt transition to air-layer drag reduction , 2008, Journal of Fluid Mechanics.

[15]  P. Spalart.  A One-Equation Turbulence Model for Aerodynamic Flows , 1992 .

[16]  B. P. Leonard,et al.  A stable and accurate convective modelling procedure based on quadratic upstream interpolation , 1990 .

[17]  Steven Deutsch,et al.  Microbubble drag reduction in liquid turbulent boundary layers , 1992 .