The boundary layer equations for plane, incompressible, and steady flow are 

$$\matrix{ {u{{\partial u} \over {\partial x}} + v{{\partial u} \over {\partial y}} = - {1 \over \varrho }{{\partial p} \over {\partial x}} + v{{{\partial ^2}u} \over {\partial {y^2}}},} \cr {0 = {{\partial p} \over {\partial y}},} \cr {{{\partial u} \over {\partial x}} + {{\partial v} \over {\partial y}} = 0.} \cr }$$

Boundary Layer Theory

Wing-in-ground effect vehicles

Marine propellers and propulsion

The paper presents the detailed formulation and validation results of simple and robust procedures for the generation of synthetic turbulence aimed at providing artificial turbulent content at the RANS-to-LES interface within a zonal Wall Modelled LES of attached and mildly separated wall-bounded flows. There are two versions of the procedure. The aerodynamic version amounts to a minor modification of a synthetic turbulence generator developed by the authors previously, but the acoustically adapted version is new and includes an internal damping layer, where the pressure field is computed by “weighting” of the instantaneous pressure fields from LES and RANS. This is motivated by the need to avoid creating spurious noise as part of the turbulence generation. In terms of pure aerodynamics, the validation includes canonical shear flows (developed channel flow, zero pressure gradient boundary layer, and plane mixing layer), as well as a more complex flow over the wall-mounted hump with non-fixed separation and reattachment, with emphasis on a rapid conversion from modeled to resolved Reynolds stresses. The aeroacoustic applications include the flow past a trailing edge and over a two-element airfoil configuration. In all cases the methodology ensures a very acceptable accuracy for the mean flow, turbulent statistics and, also, the near- and far-field noise.

Synthetic Turbulence Generators for RANS-LES Interfaces in Zonal Simulations of Aerodynamic and Aeroacoustic Problems

Research activities on inflow turbulence generation methods have been vigorous over the past quarter century, accompanying advances in eddy-resolving computations of spatially developing turbulent flows with direct numerical simulation, large-eddy simulation (LES), and hybrid Reynolds-averaged Navier-Stokes–LES. The weak recycling method, rooted in scaling arguments on the canonical incompressible boundary layer, has been applied to supersonic boundary layer, rough surface boundary layer, and microscale urban canopy LES coupled with mesoscale numerical weather forecasting. Synthetic methods, originating from analytical approximation to homogeneous isotropic turbulence, have branched out into several robust methods, including the synthetic random Fourier method, synthetic digital filtering method, synthetic coherent eddy method, and synthetic volume forcing method. This article reviews major progress in inflow turbulence generation methods with an emphasis on fundamental ideas, key milestones, representati...

Inflow Turbulence Generation Methods

Influence of the Reynolds number and the spherical dimple depth on turbulent heat transfer and hydraulic loss in a narrow channel

Flow structures and heat transfer on dimples in a staggered arrangement

A new method for synthesis of artificial turbulent fields is proposed. The idea of the method is based on the representation of the turbulent field as a collection of randomly placed spots with an unknown inner distribution of velocity determined from the prescribed autocorrelation functions. The proposed algorithm generates fluctuations with prescribed spatial integral length scales, integral time scales, two-point spatial and one-point temporal autocorrelations, as well as one-point cross correlations between fluctuation components. Copyright © 2006 John Wiley & Sons, Ltd.

Method of random spots for generation of synthetic inhomogeneous turbulent fields with prescribed autocorrelation functions

Vortex mechanism of heat transfer enhancement in a narrow channel with dimples has been investigated numerically using LES and URANS methods. The flow separation results in a formation of vortex structures which significantly enhance heat transfer on dimpled surfaces leading to a small increase in pressure loss. The heat transfer can be significantly increased by rounding the dimple edge and use of oval dimples. To get a deep insight into flow physics LES is performed for single phase flow in a channel with a spherical dimple. The instantaneous vortex formation and separation are investigated in and around the dimple area. Considered are Reynolds numbers (based on dimple print diameter) ReD = 20,000 and ReD = 40,000 the depth to print diameter ratio of Δ = 0.26. Frequency analysis of LES data revealed the presence of dominating frequencies in unsteady flow oscillations. Direct analysis of the flow field revealed the presence of coherent vortex structure inclined to the mean flow. The structure changes its orientation in time causing the long period oscillations with opposite-of-phase motion. Three dimensional proper orthogonal decomposition (POD) analysis is carried out on LES pressure and velocity fields to identify spatio-temporal structures hidden in the random fluctuations. Tornado-like spatial POD structures have been determined inside dimples.

Vortex mechanism of heat transfer enhancement in a channel with spherical and oval dimples

The Wing-In-Ground craft (WIG), a vehicle flying in
the ground effect, is a promising transportation means
of the near future. This paper describes mathematical
modeling of WIG motion in all regimes, such as
planing, take-off, transition to flight, and flight itself.
The model, which includes nonlinear hydroaerodynamics,
serves as a base for simulation of
motion. The theory developed here enhances the
process of designing WIG vehicles; its advantages and
disadvantages are discussed. The results of numerical
modeling are compared with experimental data
obtained for planing and flight regimes of motion. The
model is applied for studying emergency problems in
WIG operation.

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Nikolai Kornev

Papers

Influence of the Reynolds number and the spherical dimple depth on turbulent heat transfer and hydraulic loss in a narrow channel

Flow structures and heat transfer on dimples in a staggered arrangement

Method of random spots for generation of synthetic inhomogeneous turbulent fields with prescribed autocorrelation functions

Vortex mechanism of heat transfer enhancement in a channel with spherical and oval dimples

Complex numerical modeling of dynamics and crashes of wing-in-ground vehicles