Computational Fluid Dynamics

In a 1986 report from the National Research Council on “Current Capabilities and Future Directions in Computational Fluid Dynamics”, it was stated “computational fluid dynamics is capable of simulating flow in complex geometries with simple physics or flow with simple geometries with more complex physics”. This is not true anymore thanks to progress in computers and algorithm developments. 3D Euler calculations of flows for complex geometries that were “state of the art” in 1986 for both the hardware and software requirements can now be carried out on laptops. CFD is widely accepted as a key tool for aerodynamic design. Reynolds Average Navier-Stokes (RANS) solutions are a common tool, and methodologies like Large Eddy Simulation (LES) that were once confined to simple canonical flows (isotropic turbulence in a box, channel flow), are moving to complex engineering applications. For example, the Center for Integrated Turbulence Simulations here at Stanford is using LES to simulate the reacting flow in a real combustor chamber of a jet engine.

Abstract: Computational Fluid Dynamics (CFD) has numerous applications in the field of energy research, in modelling the basic physics of combustion, multiphase flow and heat transfer; and in the simulation of mechanical devices such as turbines, wind wave and tidal devices, and other devices for energy generation. With the constant increase in available computing power, the fidelity and accuracy of CFD simulations have constantly improved, and the technique is now an integral part of research and development. In the past few years, the development of multiscale methods has emerged as a topic of intensive research. The variable scales may be associated with scales of turbulence, or other physical processes which operate across a range of different scales, and often lead to spatial and temporal scales crossing the boundaries of continuum and molecular mechanics.

ABSTRACT Hypersonic flows are characterised by high Mach number and high total enthalpy. An elevated temperature often results in thermo-chemical reactions in the gas, which play a major role in aerothermodynamic characterisation of high-speed aerospace vehicles. Hypersonic flows in propulsion components are usually turbulent, resulting in additional effects. Computational simulation of such flows, therefore, need to account for a range of physical phenomena. Further, the numerical challenges involved in resolving strong gradients and discontinuities add to the complexity of computational fluid dynamics (CFD) simulation. In this article, physical modelling and numerical methodology-related issues involved in hypersonic flow simulation are highlighted. State-of-the-art CFD challenges are discussed in the context of two prominent applications–the flow in a scramjet inlet and the flow field around a re-entry capsule.

Meshfree methods for computational fluid dynamics P. Niedoba 1 , a , L. ˇ Cerm´ak 1 , and M. J´ıcha 1 1 Faculty of Mechanical Engineering, Brno University of Technology, Technick´a 2896 / 2, 616 69 Brno, Czech Republic Abstract. The paper deals with the convergence problem of the SPH (Smoothed Particle Hydrodynamics) meshfree method for the solution of fluid dynamics tasks. In the introductory part, fundamental aspects of mesh- free methods, their definition, computational approaches and classification are discussed. In the following part, the methods of local integral representation, where SPH belongs are analyzed and specifically the method RKPM (Reproducing Kernel Particle Method) is described. In the contribution, also the influence of boundary conditions on the SPH approximation consistence is analyzed, which has a direct impact on the convergence of the method.

Research Scholar, JJT University, Jhunjhunu, Rajasthan, India ABSTRACT- In the present article I would like to stress on the potential research agenda for lasting reforms in the area of computational fluid dynamics. On the theoretical frameworks, I have tried to propose that a scope for lots of research is required in this area of fluid dynamics. On the basis of varied problem domains carried out in this research area in the past, we can find out varied extensive applications like in transportation, microelectronics and renewable energy resources. I would like to specially adhere to its potential applications and findings in the area of energy renewable sources. Whenever an energy scientist or engineer undertake some project for installation, then his prime focus is on maximizing the output and minimizing the cost, so computational fluid dynamics helps him to achieve his goal fruitfully thus saving time, money and conserving the efficiency. In the present communication I have tried to enlist the impact of computational fluid dynamics on renewable energy sources.

Background. Computational fluid dynamics is by now a generally recognized subdis- cipline of fluid dynamics, complementing (and now often supplanting) use of theory and ex- perimentation in the analysis of fluid behavior from sub-micro scales to intergalactic cosmo- logical distances. CFD is highly interdisciplinary, as hinted by the accompanying figure, and due to this it can be approached for study from a number of different directions; correspondingly, its potential applications are essentially unlim- ited. Examples that are currently of very high in- terest include biological flows (e.g., air in respira- tory systems and blood in circulatory systems of animals), flows in porous media (e.g., remedia- tion of contaminated ground water, extraction of oil from marginal deposits), and combusting flows (e.g., for higher energy conversion efficien- cies and less pollutant production). Thus, compe-

sdedhjc@nus.edu.sg, sdemalon@nus.edu.sg Abstract. Computational fluid dynamics (CFD) is a method of solving and analysing problems that involved fluid flows. In the field of archi- tecture, urban design and urban planning, CFD is useful for the analy- sis of ventilation and airflow in the built environment, especially in very dense cities. This paper will look into the possibility of making CFD more accessible to the general design and planning field. A simu- lation is done on a urban design proposal to quickly see how air flow behaves around it. From there, it looks into the future where technology will make CFD simulation more easily adopted and the possibilities of integrating the ventilation analysis with other environmental analysis results into the urban design arena.

Preface My goal in this book entitled Introduction to Theoretical and Computational Fluid Dynamics is to provide a comprehensive and rigorous introduction to the fundamental concepts and basic equations of fluid dynamics, and simultaneously illustrate the application of numerical methods for solving a broad range of fundamental and practical problems involving incompressible Newtonian fluids. The intended audience includes advanced undergraduate students, graduate students, and researchers in most fields of science and engineering, applied mathematics, and scientific computing. Prerequisites are a basic knowledge of classical mechanics, intermediate calculus, elementary numerical methods, and some familiarity with computer programming. The chapters can be read sequentially, randomly, or in parts, according to the reader’s experience, interest, and needs.

Received: 3 June 2015 / Accepted: 23 October 2015 © The Author(s) 2015. This article is published with open access at Springerlink.com Abstract Due to recent advances in fast iterative solvers in the field of computational fluid dynamics, more complex problems which were previously beyond the scope of standard techniques can be tackled. In this paper, we describe one such situation, namely, modelling the interaction of flow and molecular orientation in a complex fluid such as a liquid crystal. Specifically, we consider a nematic liquid crystal in a spatially inhomogeneous flow situation where the orientational order is described by a second rank alignment tensor. The evolution is determined by two coupled equations:

Eaton’s computational fluid dynamics service lets customers choose from preset service levels or customize the service to meet their specific needs. The level of CFD Service determines how much information is available about the performance of your data center environment and accuracy of recommended data center solutions.

JEB0232 The hydrodynamics and undulating propulsion of tadpoles were studied using a newly developed two- dimensional computational fluid dynamics (CFD) modeling method. The mechanism of thrust generation associated with the flow patterns during swimming is discussed. Our CFD analysis shows that the kinematics of tadpoles is specifically matched to their special shape and produces a jet-stream propulsion with high propulsive efficiency, as high as that achieved by teleost fishes. Investigation of the effect of Reynolds number indicates that the Froude efficiency increases with increasing Reynolds number with no ceiling in generating the jet-stream propulsion. Further

spray drying / simulation / computational fluid dynamics Résumé – Application de la dynamique des fluides calculée par ordinateur (CFD) au séchage par atomisation. Dans l’analyse de la dynamique des fluides dans les tours de séchage par atomi- sation, le modèle d’Euler-Lagrange est utilisé pour calculer les déplacements des gouttelettes et les transferts de chaleur et de masse entre les gouttelettes et le flux d’air. Ces calculs sont réalisés pour des centaines à des dizaines de milliers de gouttelettes pour représenter la pulvérisation dans la tour de séchage. Un facteur limitant dans le transfert de masse au cours du séchage est la diffusion interne d’eau à l’intérieur des particules partiellement séchées. Pour modéliser cette diffusion interne d’eau, chaque particule est représentée par une série de coquilles sphériques concentriques. La résolution d’une équation de diffusion mono-dimensionnelle sur ces sphères permet d’obtenir la distribution et la diffusion interne d’eau dans chaque particule. Un atout majeur de la CFD réside dans la possiblité de mener rapidement des analyses d’évaluation et d’optimisation. Par exemple, un équipement de séchage avec un jeu donné de paramètres d’alimentation a été étudié. Les simulations CFD ont été réalisées dans le but de déterminer les conditions optimales pour l’air de séchage. Les informations- clés d’intérêt pour l’opérateur ont été extraites des résultats de CFD et présentées en pourcentages de particules quittant les sorties, et les caractéristiques des particules à ces sorties en termes de dia- mètre moyen, de température et de teneur en humidité. A partir de ces résultats, l’opérateur de la

ABSTRACT Solar greenhouse dryer is an instrument used for drying of crops which are needed to be preserved for consumption throughout the year. In recent years, a lot of research has been done to enhance the drying rate of crops. Many researchers have worked experimentally and recently Computational Fluid Dynamics (CFD) as a tool has been used many researchers. Change in the design and operating parameters have been made to study their effect on the performance of greenhouse dryer. In the present paper, a review regarding advances in the solar greenhouse dryers has been presented.

Computational Fluid Dynamics or Wind Tunnel Modeling? J.D. McAlpine, Envirometrics, Inc. CFD holds great promise for replacing the wind tunnel in coming years as the science behind CFD improves and computers become more powerful. Currently, CFD can provide results almost as accurate as a wind tunnel that are often more useful due to the sophisticated visualization and domain wide measurements characteristic of CFD. For building services, CFD is an effective tool for simulating wind climate to analyze pedestrian comfort, and pollution dispersion. It can also be used to assist engineers with natural ventilation design and building wind loading.

2. Computational fluid dynamics in the building industry Computational fluid dynamics (CFD) is a branch of fluid mechanics that uti- lises numerical methods to solve and analyse problems involving fluid flows. CFD has been commercially available since the early 1980s in the engineer- ing community for applications such as turbo machinery, aerospace, com- bustion, and mechanical engineering. Today, CFD has proven to be a driving factor for performance enhancement in areas as diverse as Formula 1 racing, naval architecture for the America’s Cup, and product development for swimwear; it has grown into an industry worth approximately 800 million dollars annually (Hanna, 2012).

26 2.2 Computational Methods for Fluid Dynamics Computational fluid dynamics, or usually abbreviated as CFD, is a tool that can be utilised for analysing problems involve fluid flow with partial differential equations based on conservation of mass, energy and momentum. In the past few decades, thanks to the remarkable advance of computer technology, the use of CFD for the evaluation of the environments in buildings has been increasingly popular and important. CFD can be used to provide information to analyse the influence of exhaust pollution on the environments, indoor smoke and fire risks, ventilation effectiveness and air quality. This section examines the modelling methods of computational fluid dynamics with introducing the approaches used for analysing turbulent flows including turbulence modelling, various turbulent models and wall functions.

6. CONCLUSION Computational Fluid Dynamics (CFD) tools used in shipbuilding industry involve multiple disciplines. Traditionally, the analysis was performed separately and sequentially in each discipline with low integration, which often resulted in conflict and inconsistency of hydrodynamic prediction. This paper presented a Virtual Integration Platform (VIP) developed in the University of Strathclyde within two EU funded projects – VIRTUE and SAFEDOR, under the FP6 framework. The VIP provides a holistic collaborative environment for designers with features such as Project/Process Management, Distributed Tools Integration, Process visualisation, Consistency Management, Version Management, Enable Multiple results Visualisation, Global Optimisation, Decentralised Data Management, and Knowledge Management. These features enhance collaboration among customers, ship design companies, shipyards and consultancies. Moreover, its advances in time efficiency, facilitate testing developing CFD tools, error free enactment, and cost efficiency have been revealed through ten case studies across seven ship design companies and consultancies. Though there are still plans for the further development of the VIP, it has been demonstrated as a unique platform for future CFD computations.

Abstract- The steady improvement in the speed of computers and the memory size since the 1950’s has led to the emergence of computational fluid dynamics (CFD). It is a branch of fluid dynamics uses numerical methods such as the Navier-Stokes and allied equations to solve the fundamental nonlinear differential equations that describe fluid flow for predefined geometries and boundary conditions. The result is a wealth of predictions for flow velocity, temperature, density, and chemical concentrations for any region where flow occurs. In recent years field of CFD has grown tremendously over the past few decades. It is widely used in various engineering applications, especially in aircraft design; also its use in construction industry has been seen over the past few years. It has been a very helpful tool to solve the various flow related equations, which cannot be solved by using analytical methods. The main aim of CFD is to solve the basic flow related equations which describe the movements and other characteristics of the flow. In recent times, the techniques of CFD has been used almost in every industry where flow issues are to be solved, it has wide range of applications in Aerospace and Constructional Industry.

Previous publications show that Computational Fluid Dynamics (CFD) can be readily used for the flow prediction and analysis of screw compressors. Several case studies are presented in this paper to show the scope and applicability of such methods. These include solid-fluid interaction in screw compressors, prediction of flow generated noise in screw machines, cavitation modelling in gear pumps, and flow in multiphase pumps for oil and gas industry. Numerical grids for all these cases were generated by us of an in-house grid generator, while the CFD calculations were performed with a variety of commercially available CFD codes.

Imagine a situation in which two paratroopers, jumping from both side doors of a military cargo aircraft, always crash into each other down below (3). In order to analyze the fluid dynamics of the problem to see what air flow forces are affecting the paratrooper paths, you would need to perform test jumps with paratroopers. However, that is potentially injurious and not safe. You would also have to rent the plane, pay for the rental by hour, hire the test pilot, and pay for all the equipment for the jump. That is expensive. Lastly, the organization of the use of the military aircraft and personnel and equipment takes many months, and it can take from 6 to 12 months to plan the test. In this case a CFD experiment is more convenient: faster, cheaper, and safer.