Virtual Control Volumes for Three-Dimensional Unstructured Elliptic Smoothing

2011 ◽  
Author(s):  
Steve Karman
Keyword(s):  
Three Dimensional ◽  
Virtual Control ◽  
Elliptic Smoothing ◽  
Control Volumes

Numerical Investigation of the Unsteady Transonic 3D-Flow in Stator and Rotor Cascades With Oscillating Blades

1996 ◽  
Author(s):  
Dieter Peitsch ◽  
Heinz E. Gallus ◽  
Stefan Weber
Keyword(s):  
Control Volume ◽  
Torsional Oscillation ◽  
Three Dimensional ◽  
Tvd Scheme ◽  
Special Technique ◽  
Computer Memory ◽  
Computational Domain ◽  
Flux Limiter ◽  
Oscillation Modes ◽  
Control Volumes

Subject of this paper is a numerical method for the simulation of flutter in three dimensional oscillating cascades. Unsteadiness can be caused by bending and torsional oscillation modes simultaneously. The goal of the investigation is the evaluation of the resulting blade forces and moments. The flow is assumed to be time-dependent and inviscid. By solving the Euler equations in a nonlinear way, large oscillations as well of the airfoil as of existing shocks can be treated. The numerical solution follows a Godunov-type upwind scheme, formulated in node centered finite volume technique. An approximative Riemann solver proposed by Roe is used to determine the fluxes over the surfaces of the control volume. Since unphysical expansion shocks have to be suppressed, a modification of the transonic characteristic speeds is included. The extrapolation of the flow values onto the control volumes’ surfaces is done by means of the MUSCL technique, embedded in a TVD-scheme with the flux limiter by van Albada. The computational domain is restricted to only one channel and the periodic values are stored over one period of oscillation. A special technique is introduced, which reduces both the effort in CPU-time and in computer memory. Results are included for compressor and turbine geometries in sub- and transonic flow.

Shaping the Combustion Chamber of a Piston Engine with Direct Injection of Gasoline

2019 ◽  
pp. 67-76
Author(s):  
R.Z. Kavtaradze ◽  
A.A. Kasko ◽  
A.A. Zelentsov
Keyword(s):  
Combustion Chamber ◽  
Direct Injection ◽  
Combustion Process ◽  
Three Dimensional ◽  
Numerical Control ◽  
Engine Operation ◽  
Model Fuel ◽  
Nonstationary Equations ◽  
Current Lines ◽  
Control Volumes

The object of the study was a six-cylinder in-line engine for land transport system with direct gasoline supply and forced ignition. The problem of shaping the combustion chamber is solved using the numerical control volumes method in a three-dimensional formulation. Nonstationary equations of energy, motion, diffusion and continuity in the Reynolds form, supplemented by the k-ζ-f model of turbulence, are used as a basis for modelling the engine operation. To model fuel combustion, an extended coherent flame model (ECFM) was used. Calculations were performed using the AVL FIRE software. The processes of mixture formation were optimized by considering the current lines and velocity fields of a moving charge, taking into account the geometry of the combustion chamber and intake and exhaust ports. As a result, the efficiency of the engine increased and the combustion process became more stable in the part load modes employing different fuel supply laws.

A VoF-Based Consistent Mass-Momentum Transport for Two-Phase Flow Simulations

2017 ◽  
Author(s):  
Annagrazia Orazzo ◽  
Isabelle Lagrange ◽  
Jean-Luc Estivalézes ◽  
Davide Zuzio
Keyword(s):  
Density Ratio ◽  
Three Dimensional ◽  
Industrial Applications ◽  
High Density ◽  
Momentum Transport ◽  
Two Phase ◽  
Mass Fluxes ◽  
Numerical Instabilities ◽  
Density Ratios ◽  
Control Volumes

The most part of two-phase flows relevant to industrial applications is characterized by high density ratios that make numerical simulations of such kind of flows still challenging in particular when the interface assumes complex shape and is distorded by high shear. In this paper a new strategy, to overcome the numerical instabilities induced by the large densities/shears at the interface, is described for staggered cartesian grids. It consists in a consistent mass-momentum advection algorithm where mass and momentum transport equations are solved in the same control volumes. The mass fluxes are evaluated through the Volume-of-Fluid color function and directly used to calculate momentum convective term. Two and three-dimensional high-density test cases (the density ratio goes from 103 to 109) are presented. The new algorithm shows signifcantly improvements compared to standard advection methods therefore suggesting the applicability to the complete atomization process simulations.

scholarly journals Higher-Order Accurate Finite Volume Discretization of the Three-Dimensional Poisson Equation Based on An Equation Error Method

2018 ◽  
Vol 6 (6) ◽  
pp. 107-123
Author(s):  
Yaw Kyei
Keyword(s):  
Finite Volume ◽  
Three Dimensional ◽  
Integral Form ◽  
Higher Order ◽  
Finite Volume Schemes ◽  
Finite Volume Discretization ◽  
Equation Error ◽  
Error Expansion ◽  
Control Volumes ◽  
Physical Phenomena

Efficient higher-order accurate finite volume schemes are developed for the threedimensional Poisson’s equation based on optimizations of an equation error expansion on local control volumes. A weighted quadrature of local compact fluxes and the flux integral form of the equation are utilized to formulate the local equation error expansions. Efficient quadrature weights for the schemes are then determined through a minimization of the error expansion for higher-order accurate discretizations of the equation. Consequently, the leading numerical viscosity coefficients are more accurately and completely determined to optimize the weight parameters for uniform higher-order convergence suitable for effective numerical modeling of physical phenomena. Effectiveness of the schemes are evaluated through the solution of the associated eigenvalue problem. Numerical results and analysis of the schemes demonstrate the effectiveness of the methodology.

Heat Transfer in Film-Cooled Turbine Blades

1993 ◽  
Author(s):  
Vijay K. Garg ◽  
Raymond E. Gaugler
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Film Cooling ◽  
Stokes Equations ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Explicit Finite Difference ◽  
Control Volumes

In order to study the effect of film cooling on the flow and heat transfer characteristics of actual turbine blades, a three-dimensional Navier-Stokes code has been developed. An existing code (Chima and Yokota, 1990) has been modified for the purpose. The code is an explicit finite difference code with an algebraic turbulence model. The thin-layer Navier-Stokes equations are solved using a general body-fitted coordinate system. The effects of film cooling have been incorporated into the code in the form of appropriate boundary conditions at the hole locations on the blade surface. Each hole exit is represented by several control volumes, thus providing an ability to study the effect of hole shape on the film-cooling characteristics. Comparison with experimental data is fair. Further validation of the code is required, however, and in this respect, there is an urgent need for detailed experimental data on actual turbine blades.

Application of High-Resolution Spatial Discretization Schemes to Volume-of-Fluid Simulations on Three-Dimensional Unstructured Meshes

2007 ◽  
Author(s):  
D. Keith Walters
Keyword(s):  
High Resolution ◽  
Volume Fraction ◽  
Phase Interface ◽  
Three Dimensional ◽  
Volume Of Fluid ◽  
Unstructured Meshes ◽  
Spatial Discretization ◽  
Upwind Schemes ◽  
Discretization Schemes ◽  
Control Volumes

The interface capturing approach to volume-of-fluid (VOF) simulation relies on high-resolution spatial discretization of the volume fraction equation, without explicit reconstruction of the phase interface within computational control volumes. One advantage of this approach is that it may be applied on general topology meshes in a straightforward manner. This paper investigates the performance of two different high-resolution discretization schemes used for the solution of the volume fraction equation on three-dimensional unstructured meshes. The schemes are used to obtain results for several simple test problems, including convection of a round and a square phase profile in a uniform fluid stream, two-phase oil and water flow in an inclined channel, and convection of a round jet-in-crossflow. The performance of the two schemes is compared in terms of their ability to minimize the effects of numerical dissipation, which tends to “smear” the phase interface over several computational control volumes. It is shown that a recently proposed scheme that relies on maximization of the volume fraction gradient in the region of the interface yields substantially better results than a more commonly used NVD (normalized variable diagram) based scheme, as well as traditional first and second-order upwind schemes.

scholarly journals Situational Modeling Technology in Virtual Environment Systems

2021 ◽  
Vol 24 (5) ◽  
pp. 889-901
Author(s):  
Михаил Васильевич Михайлюк ◽  
Дмитрий Алексеевич Кононов ◽  
Дмитрий Михайлович Логинов
Keyword(s):  
Virtual Environment ◽  
Outer Space ◽  
Three Dimensional ◽  
Computer Screen ◽  
Modeling Technology ◽  
Virtual Control ◽  
Artificial Environment ◽  
Three Dimensional Models ◽  
Special Editor ◽  
Special Language

The technology of modelling various situations in virtual environment systems, which are computer three-dimensional models of a real or artificial environment, is discussed. The user can view these scenes directly on the computer screen, wall screen, in a stereo glasses, virtual reality glasses, etc. He can also move inside a virtual scene and interact with its objects. In turn, the environment can also change. This allows modelling of various situations (situation modelling) in the virtual environment system. With such modelling, some static or dynamic situation is set in the virtual environment system in which the operator must perform the tasks assigned to him. A mechanism for setting situations by changing a virtual three-dimensional scene using configuration files and virtual control panels is proposed. A special language has been developed for writing configuration files, and a special editor has been developed for creating virtual control panels. The approbation of the proposed methods is presented on the examples of two virtual scenes: a training ground for mobile robots and a jet backpack for the rescue of an astronaut in outer space.

scholarly journals Modeling the airflow field of vortex spinning

2021 ◽  
pp. 004051752110569
Author(s):  
Shanshan Shang ◽  
Zikai Yu ◽  
Guangwu Sun ◽  
Chongwen Yu ◽  
R Hugh Gong ◽  
...  
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Wall Function ◽  
Great Insight ◽  
Spinning Process ◽  
Turbulent Airflow ◽  
Region Model ◽  
Airflow Field ◽  
Control Volumes ◽  
Insight Into

Vortex spinning technology adopts a high-speed swirling airflow to rotate the fibers with open-ends to form yarn with real twists. The airflow behavior within the nozzle has a great effect on the yarn-formation process. In this study, a three-dimensional calculation nozzle model and corresponding three-dimensional airflow region model were established to enable the numerical calculation; airflow behavior—pressure, velocity, and the turbulent airflow field, and the streamline of airflow—was investigated in the presence of fiber bundles within the vortex spinning nozzle. Hybrid hexahedral/tetrahedral control volumes were utilized to mesh the grids in the calculation region. To consider airflow diffusion and convection in the nozzle, the Realizable k- ε turbulence model with wall function was adopted to conduct the calculation. Dynamic and static pressure values were obtained by numerical analysis to predict the action of the inner surface of nozzle and the wall resistance on the high-speed swirling airflow. The numerical simulation of dynamic airflow behavior can generate great insight into the details of airflow behavior and its distribution characteristics, and is helpful for understanding the spinning mechanism and promoting optimization of the spinning process.

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