Automatic Differentiation of the General-Purpose Computational Fluid Dynamics Package FLUENT

2006 ◽  
Vol 129 (5) ◽  
pp. 652-658 ◽  
Author(s):  
Christian H. Bischof ◽  
H. Martin Bücker ◽  
Arno Rasch ◽  
Emil Slusanschi ◽  
Bruno Lang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Automatic Differentiation ◽  
General Purpose ◽  
Computational Techniques ◽  
Software Packages ◽  
Broad Variety ◽  
Industrial Software ◽  
Crucial Ingredient ◽  
Numerical Approaches

Derivatives are a crucial ingredient to a broad variety of computational techniques in science and engineering. While numerical approaches for evaluating derivatives suffer from truncation error, automatic differentiation is accurate up to machine precision. The term automatic differentiation comprises a set of techniques for mechanically transforming a given computer program to another one capable of evaluating derivatives. A common misconception about automatic differentiation is that this technique only works on local pieces of fairly simple code. Here, it is shown that automatic differentiation is not only applicable to small academic codes, but scales to advanced industrial software packages. In particular, the general-purpose computational fluid dynamics software package FLUENT is transformed by automatic differentiation.

Direct Sensitivity Analysis of Multibody Systems: A Vehicle Dynamics Benchmark

2019 ◽  
Vol 14 (2) ◽  
Author(s):  
Alfonso Callejo ◽  
Daniel Dopico
Keyword(s):  
Sensitivity Analysis ◽  
Multibody Systems ◽  
Automatic Differentiation ◽  
Time Integration ◽  
General Purpose ◽  
Contact Forces ◽  
Design Parameters ◽  
Computational Techniques ◽  
Computationally Efficient ◽  
Integration Algorithm

Algorithms for the sensitivity analysis of multibody systems are quickly maturing as computational and software resources grow. Indeed, the area has made substantial progress since the first academic methods and examples were developed. Today, sensitivity analysis tools aimed at gradient-based design optimization are required to be as computationally efficient and scalable as possible. This paper presents extensive verification of one of the most popular sensitivity analysis techniques, namely the direct differentiation method (DDM). Usage of such method is recommended when the number of design parameters relative to the number of outputs is small and when the time integration algorithm is sensitive to accumulation errors. Verification is hereby accomplished through two radically different computational techniques, namely manual differentiation and automatic differentiation, which are used to compute the necessary partial derivatives. Experiments are conducted on an 18-degree-of-freedom, 366-dependent-coordinate bus model with realistic geometry and tire contact forces, which constitutes an unusually large system within general-purpose sensitivity analysis of multibody systems. The results are in good agreement; the manual technique provides shorter runtimes, whereas the automatic differentiation technique is easier to implement. The presented results highlight the potential of manual and automatic differentiation approaches within general-purpose simulation packages, and the importance of formulation benchmarking.

A Survey of General Purpose Computation of GPU for Computational Fluid Dynamics

2013 ◽  
Vol 753-755 ◽  
pp. 2731-2735
Author(s):  
Wei Cao ◽  
Zheng Hua Wang ◽  
Chuan Fu Xu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Performance ◽  
Stokes Equations ◽  
Gpu Computing ◽  
Graphics Processing Unit ◽  
General Purpose ◽  
Navier Stokes ◽  
Processing Unit ◽  
Gpgpu Computing

The graphics processing unit (GPU) has evolved from configurable graphics processor to a powerful engine for high performance computer. In this paper, we describe the graphics pipeline of GPU, and introduce the history and evolution of GPU architecture. We also provide a summary of software environments used on GPU, from graphics APIs to non-graphics APIs. At last, we present the GPU computing in computational fluid dynamics applications, including the GPGPU computing for Navier-Stokes equations methods and the GPGPU computing for Lattice Boltzmann method.

Customized CFD for VIV: Advantages and Applications

2012 ◽  
Author(s):  
Oliver Heynes
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Conventional Method ◽  
General Purpose ◽  
Dynamics Modeling ◽  
Numerical Techniques ◽  
Computational Fluid Dynamics Modeling ◽  
Vortex Induced Vibrations ◽  
Simulation Time

A new concept is introduced in the field of Computational Fluid Dynamics modeling of vortex-induced-vibrations: a CFD code written specifically for modeling riser VIV. The concept of the “single-purpose” CFD code has numerous advantages over the conventional method of running a simulation within “general-purpose” CFD software. By virtue of choosing the most efficient numerical techniques for the type of flow encountered, accurate solutions can be obtained two orders of magnitude quicker than the equivalent simulation using general-purpose CFD software. This is demonstrated through several examples, where accurate run times are obtained within a few seconds of simulation time.

scholarly journals Trim Influence on Kriso Container Ship (KCS): An Experimental and Numerical Study

2017 ◽  
Author(s):  
Emil Shivachev ◽  
Mahdi Khorasanchi ◽  
Alexander H. Day
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Study ◽  
Computational Cost ◽  
Breaking Waves ◽  
Computational Techniques ◽  
Container Ship ◽  
Towing Tank ◽  
Operational Life ◽  
Computational Fluid Dynamics Cfd

There has been a lot of interest in trim optimisation to reduce fuel consumption and emissions of ships. Many existing ships are designed for a single operational condition with the aim of producing low resistance at their design speed and draft with an even keel. Given that a ship will often sail outside this condition over its operational life and moreover some vessels such as LNG carriers return in ballast condition in one leg, the effect of trim on ships resistance will be significant. Ship trim optimization analysis has traditionally been done through towing tank testing. Computational techniques have become increasingly popular for design and optimization applications in all engineering disciplines. Computational Fluid Dynamics (CFD), is the fastest developing area in marine fluid dynamics as an alternative to model tests. High fidelity CFD methods are capable of modelling breaking waves which is especially crucial for trim optimisation studies where the bulbous bow partially emerges or the transom stern partially immerses. This paper presents a trim optimization study on the Kriso Container Ship (KCS) using computational fluid dynamics (CFD) in conjunction with towing tank tests. A series of resistance tests for various trim angles and speeds were conducted at 1:75 scale at design draft. CFD computations were carried out for the same conditions with the hull both fixed and free to sink and trim. Dynamic sinkage and trim add to the computational cost and thus slow the optimisation process. The results obtained from CFD simulations were in good agreement with the experiments. After validating the applicability of the computational model, the same mesh, boundary conditions and solution techniques were used to obtain resistance values for different trim conditions at different Froude numbers. Both the fixed and free trim/sinkage models could predict the trend of resistance with variation of trim angles; however the fixed model failed to measure the absolute values as accurately as the free model. It was concluded that a fixed CFD model, although computationally faster and cheaper, can find the optimum trim angle but cannot predict the amount of savings with very high accuracy. Results concerning the performance of the vessel at different speeds and trim angles were analysed and optimum trim is suggested.

Fluid-Structure Interaction Simulations of Parachute Deployment and Inflation

2021 ◽  
Author(s):  
Liwu Wang ◽  
Mingzhang Tang ◽  
Yu Liu ◽  
Sijun Zhang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Fluid Structure Interaction ◽  
Computational Approach ◽  
Computational Techniques ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Structure Dynamics ◽  
Computational Structure ◽  
Membrane Wrinkling

Abstract The numerical simulation of the parachute deployment/inflation process involves fluid structure interaction problems, the inherent complexities in the fluid structure interaction have been posing several computational challenges. In this paper a high fidelity Eulerian computational approach is proposed for the simulation of parachute deployment/inflation. Unlike the arbitrary Eulerian Lagrangian (ALE) method widely employed in this area, the Eulerian computational approach is established on three computational techniques: computational fluid dynamics, computational structure dynamics and computational moving boundary. A set of stationary, non-deforming Cartesian grids is adopted in our computational fluid dynamics, our computational structure dynamics is enhanced by non-linear finite element method and membrane wrinkling algorithm, instead of conventional computational mesh dynamics, an immersed boundary method is employed to avoid insurmountable poor grid quality brought in by moving mesh approaches. To validate the proposed numerical approach the deployment/inflation of C-9 parachute is simulated using our approach and the results show similar characteristics compared with experimental results and previous literature. The computed results have demonstrated the proposed method to be a useful tool for analyzing dynamic parachute deployment and subsequent inflation.

Harnessing the Power of the Cloud - Computational Fluid Dynamics With SimScale

2021 ◽  
Author(s):  
Jousef Murad
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Fluid Flow ◽  
High Performance ◽  
Cfd Simulation ◽  
Ease Of Use ◽  
Computational Method ◽  
Added Value ◽  
Broad Variety ◽  
Wind Comfort

Abstract Computational fluid dynamics is a computational method that enables engineers and designers to study the motion of fluids through computer simulations and modelling. Many tools on the market are so-called “in-house” tools requiring a certain level of expertise and upfront investment before proving their added value. Facilitated by the emergence of cloud computing, computer-aided engineering (CAE) technology is now offered as a software as a service (SaaS) solution, which increases its accessibility and ease of use. Online fluid flow (CFD) simulation is used in addressing a broad variety of problems like electronics design or pedestrian wind comfort (PWC), allowing engineers to accurately predict fluid flow behaviour guiding them towards smarter design decisions. SimScale is creating a paradigm shift for high-performance computing which can solve several problems that are faced when using on-premises software.

Improvement in Learning on Fluid Mechanics and Heat Transfer Courses Using Computational Fluid Dynamics

2010 ◽  
Vol 38 (2) ◽  
pp. 147-166 ◽  
Author(s):  
Blas Zamora ◽  
Antonio S. Kaiser ◽  
Pedro G. Vicente
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Fluid Mechanics ◽  
Engineering Education ◽  
Professional Training ◽  
Engineering Students ◽  
General Purpose ◽  
Project Based Learning ◽  
Computational Fluid Dynamics Cfd

This paper is concerned with the teaching of fluid mechanics and heat transfer on courses for the industrial engineer degree at the Polytechnic University of Cartagena (Spain). In order to improve the engineering education, a pedagogical method that involves project-based learning, using computational fluid dynamics (CFD), was applied. The project-based learning works well for mechanical engineering education, since it prepares students for their later professional training. The courses combined applied and advanced concepts of fluid mechanics with the basic numerical aspects of CFD, including validation of the results obtained. In this approach, the physical understanding of practical problems of fluid mechanics and heat transfer played an important role. Satisfactory numerical results were obtained by using both Phoenics and Fluent finite-volume codes. Some cases were solved using the well known Matlab software. Comparisons were made between the results obtained by analytical solutions (if any) with those reached by CFD general-purpose codes and with those obtained by Matlab. This system provides engineering students with a solid comprehension of several aspects of thermal and fluids engineering.

The Application of Advanced Computational Methods to the Modeling of PBMR Source Terms

2004 ◽  
Author(s):  
Margaret Msongi Mkhosi ◽  
Richard Denning ◽  
Shoichiro Nakamura
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Reynolds Number ◽  
Radioactive Material ◽  
Dust Particles ◽  
Integrated Analysis ◽  
Computational Techniques ◽  
Turbulent Regime ◽  
Pebble Bed

The pebble bed modular reactor (PBMR) is a high temperature gas-cooled reactor which uses helium gas as a coolant. The PBMR design relies on the excellent heat transfer properties of graphite and a fuel design that is inherently resistant to the release of the radioactive material up to high temperatures. The safety characteristics of the PBMR concept are excellent. However, a very strong safety case will have to be made if a new generation of reactors is to be successfully introduced to a concerned public. Until recent developments in computational fluid dynamics methods, computer speed, and data storage, the coupled thermal-hydraulic, chemical, and mass transport phenomena could not be treated in an integrated analysis. This paper addresses one aspect of the interplay between the details of fluid flow and aerosol transport within the complex geometry of the pebble bed core. A very large quantity of graphite dust is produced by the interaction among the pebbles. The potential for the deposition of radionuclides on the surface of dust particles and their subsequent transport as aerosols is substantial. This effort focuses on the inertial deposition of these aerosols within the pebble bed. Inertial deposition in the low Reynolds number regime of laminar flow in pebble beds has been explored previously, but with less powerful computational techniques. Some experimental data are also available in this regime. No analyses or experimental data are available in the high Reynolds number turbulent regime in which the PBMR operates. This paper describes results of analyses of inertial deposition obtained with the FLUENT computational fluid dynamics code. The objective of the analysis is to obtain an expression for deposition within an asymptotic unit cell, removed from the boundary conditions at the entrance to the array. The results of analyses performed at different velocities and fluid densities in the turbulent regime were correlated against a modified Stokes number. The deposition correlation is well represented by the integral form of the normal distribution. Deposition for the time-averaged flow was found to be insensitive to the flow model. In the laminar regime, FLUENT results were found to be in agreement with earlier published results and experimental data. The stochastic behavior of eddies was also simulated within FLUENT using the k–ε model. Eddy-enhanced deposition results in greater deposition at all aerosol sizes in comparison with the time-averaged results, with significant deposition of aerosols predicted for small aerosol sizes. However, it is likely that these results are quite sensitive to the modeling of turbulence and they must be considered preliminary.

The use of computational fluid dynamics (CFD). Technique for evaluating the efficiency of an activated sludge reactor

1999 ◽  
Vol 39 (10-11) ◽  
pp. 329-332 ◽  
Author(s):  
A. B. Karama ◽  
O. O. Onyejekwe ◽  
C. J. Brouckaert ◽  
C. A. Buckley
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Computational Techniques ◽  
Activated Sludge Reactor ◽  
Computational Fluid Dynamics Cfd ◽  
The Cost ◽  
New Generation

Adequate models for wastewater treatment are limited by the cost of constructing them. Many a time, studies carried out on wastewater treatment plants have not been very useful in enhancing their performance. As a result, numerous mathematical models presented by different researchers on sedimentation tanks and clarifiers have not been getting much attention. Recently, improvement in computers and computational techniques have led to the development of a new generation of highly efficient programs for simulating real fluid flow within any type of geometry including clarifiers and activated sludge reactors. Herein, a computational fluid dynamics code, PHOENICS, is used to determine the performance of an anaerobic zone in an activated sludge reactor. Plausible results were achieved when experimental data were compared with numerical results.

Computational Fluid Dynamics for Fixed Bed Reactor Design

2020 ◽  
Vol 11 (1) ◽  
pp. 109-130 ◽  
Author(s):  
Anthony G. Dixon ◽  
Behnam Partopour
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Rapid Development ◽  
Fixed Bed ◽  
Pilot Scale ◽  
Fixed Bed Reactor ◽  
Computational Techniques ◽  
Fixed Beds ◽  
Reactor Models ◽  
Complex Phenomena

Flow, heat, and mass transfer in fixed beds of catalyst particles are complex phenomena and, when combined with catalytic reactions, are multiscale in both time and space; therefore, advanced computational techniques are being applied to fixed bed modeling to an ever-greater extent. The fast-growing literature on the use of computational fluid dynamics (CFD) in fixed bed design reflects the rapid development of this subfield of reactor modeling. We identify recent trends and research directions in which successful methodology has been established, for example, in computer generation of packings of complex particles, and where more work is needed, for example, in the meshing of nonsphere packings and the simulation of industrial-size packed tubes. Development of fixed bed reactor models, by either using CFD directly or obtaining insight, closures, and parameters for engineering models from simulations, will increase confidence in using these methods for design along with, or instead of, expensive pilot-scale experiments.

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