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

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

Analysis of the unsteady wake of a full bottomed ship in shallow water

The paper is devoted to the analysis of the unsteady hydrodynamic processes taking place in the ship wake under shallow water conditions. The motivation of the research is the determination of the reasons for the rise of strong vibration in the stern of inland cruise ships in the waterways with considerable depth restriction. As a research tool the hybrid URANS/LES approach of Kornev et al. [1] is selected in order to capture the influence of nonstationary vortical structures on the velocity oscillations in the propeller plane. As it will be shown, URANS method cannot reproduce these flow features. The flow is studied in a single-phase and in a two-phase formulation. Influence of the free surface, depth Froude number and depth to draft ratio on the wake is analyzed. The adverse pressure gradient in the stern region causes massive separations of the boundary layer. On account of the separations the velocity oscillations in the wake are turned out to be strongly dependent on the under keel clearance. On the other hand, it is shown, that at high F rH the wave pattern can significantly influence the viscous wake and cause the suppression of the velocity oscillations due to the decrease of the water level. Possible effect of the wake unsteadiness on the propeller performance in such circumstances is discussed

Unsteady loading on the propeller at different maneuvering conditions using hybrid and urans methods

The results of computations of the unsteady wake and unsteady loadings on marine propellers behind the KVLCC2 tanker model under simple manoeuver conditions (only drift angle) and complete manoeuvring (drift angle and yaw rate) using different numerical methods are presented and analysed. The hybrid URANS-LES model presented in [1, 2], the hybrid IDDES and the k-ω-SST model are applied first for the bare hull at different drift angles, and then under complete manoeuvring conditions (different drift angles and yaw rates). The forces and moment coefficients of the bare hull calculations under different drift angels were compared with the experimental results of Kume et al. [3]. In the second series of calculations the arrangement containing both the ship and rotating propeller is computed with consideration of all interaction effects at different drift angles. Under complete manoeuvring condition the whole system (ship, rudder and propeller) was calculated using the hybrid method [1, 2]. CFD results for the time averaged thrust were compared with the experimental results [4]. Also the comparison for the standard deviations of forces and moments acting on propeller and its appendages with the experimental estimations is presented

Study of unsteady hydrodynamic effects in the stern area of river cruisers in shallow water

Abstract. The main objective of the present paper is the assessment of the influence of shallow water conditions on the hydrodynamic exciters of ship hull vibration using hybrid RANS/LES methods. The following topics will be briefly discussed: • Validation of hybrid methods for calculation of ship wake in shallow water • Analysis of the influence of different factors on the nominal wake characteristics • Assessment of thrust fluctuations and pressure pulses and their sensitivity to motion con- ditions It will be shown, that the depth restriction may influence the periodic forces and moments acting on the ship stern and by these means intensify the vibration

Extension of the turbulent spot method towards arbitrary reynolds stresses and integral lengths

The paper presents an extension of the Turbulent Spot method which enables to obey the continuity of the fluctuations while producing arbitrarily high anisotropy at the same time. The derivation of the structures is summarized and expressions for their Reynolds stresses and length scales are presented. Finally, the newly derived structures are applied to a turbulent channel flow simulation and compared with other means of turbulence synthesis

Coupled thermo- aerodynamical problems in design of protection cloth

The paper presents results of calculation of thermodynamic interaction between the human body and the ambient air at very low temperatures. The numan body is clothed in a warm coverall. Temperature transport is calculated numerically by the solution of heat conduction equation. Simplified thermodynamic model of the human body by the surface heat flux obtained from empirical data is applied. Results of investigations are used for design of real protection cloth

Development of a hybrid grid-and particle-based numerical method for resolution of fine vortex structures in fluid mechanics

The paper presents a novel hybrid approach developed to improve the resolution of concentrated vortices in computational fluid mechanics. The method is based on combination of a grid based and the grid free computational vortex (CVM) methods. The large scale flow structures are simulated on the grid whereas the concentrated structures are modeled using CVM. Due to this combination the advantages of both methods are strengthened whereas the disadvantages are diminished. The procedures of the separation of small concentrated vortices from the large scale vortices is based on LES filtering idea. The flow dynamics is governed by two coupled transport equations taking two way interaction between large and fine structures into account. The fine structures are mapped back to the grid represented large structures if their size grows due to diffusion. Algorithmic aspects of the hybrid method are discussed