A space-time parallel algorithm with adaptive mesh refinement for computational fluid dynamics

Applications of computational fluid (CFD) dynamics in agriculture and food industry are becoming important because of its versatility, accuracy and user friendliness. Now CFD is regularly used to solve environmental problems of structures and animal production systems. In the recent years this is becoming popular in drying and storage of agricultural products. This paper presents the state of art of CFD and its applications in greenhouse, animal housing, drying and storage. The potentials of CFD are also discussed.

An efficient geometry-adaptive mesh refinement framework and its application in the immersed boundary lattice Boltzmann method

The adaptive mesh refinement (AMR) method is developed for three-dimensional turbulent complex flows in clean rooms using the finite volume method with a collocated grid arrangement. Clean rooms have many interesting and complex flow characteristics especially the secondary flows and the recirculation regions. The accurate numerical solution of the flows is important for the efficient design of clean rooms. The use of the conventional uniform grid requires such a high computational time and data storage capacity that they make computational fluid dynamics (CFD) less attractive for the design optimization. The AMR method is, therefore, applied by using the fine grid only in the required regions and using the coarse grid in the other regions. The velocity is chosen as the main parameter for the grid refinement because it is the most influential parameter in clean rooms. The results show that the present AMR method can reduce the computational time by eight times and the data storage requirement is only 37% of that using the conventional method, while the same order of accuracy can be maintained. The present AMR method is, therefore, proved to be a promising technique for solving three-dimensional turbulent complex flows in clean rooms.

Computational Fluid Dynamics (CFD) applications are highly demanding for parallel computing. Many such applications have been shifted from expensive MPP boxes to cost-effective Networks of Workstations (NOW). Auto-CFD-NOW is a pre-compiler that transforms Fortran CFD sequential programs to efficient message-passing parallel programs running on NOW. Our work makes the following three unique contributions. First, this pre-compiler is highly automatic, requiring a minimum number of user directives for parallelization. Second, we have applied a dependency analysis technique for the CFD applications, called analysis after partitioning. We propose a mirror-image decomposition technique to parallelize self-dependent field loops that are hard to parallelize by existing methods. Finally, traditional optimizations of communication focus on eliminating redundant synchronizations. We have developed an optimization scheme which combines all the non-redundant synchronizations in CFD programs to further reduce the communication overhead. The Auto-CFD-NOW has been implemented on networks of workstations and has been successfully used for automatically parallelizing structured CFD application programs. Our experiments show its effectiveness and scalability for parallelizing large CFD applications.

Journal bearings are important parts to keep the high dynamic performance of rotor machinery. Some methods have already been proposed to analysis the flow field of journal bearings, and in most of these methods simplified physical model and classic Reynolds equation are always applied. While the application of the general computational fluid dynamics (CFD)-fluid structure interaction (FSI) techniques is more beneficial for analysis of the fluid field in a journal bearing when more detailed solutions are needed. This paper deals with the quasi-coupling calculation of transient fluid dynamics of oil film in journal bearings and rotor dynamics with CFD-FSI techniques. The fluid dynamics of oil film is calculated by applying the so-called “dynamic mesh” technique. A new mesh movement approach is presented while the dynamic mesh models provided by FLUENT are not suitable for the transient oil flow in journal bearings. The proposed mesh movement approach is based on the structured mesh. When the journal moves, the movement distance of every grid in the flow field of bearing can be calculated, and then the update of the volume mesh can be handled automatically by user defined function (UDF). The journal displacement at each time step is obtained by solving the moving equations of the rotor-bearing system under the known oil film force condition. A case study is carried out to calculate the locus of the journal center and pressure distribution of the journal in order to prove the feasibility of this method. The calculating results indicate that the proposed method can predict the transient flow field of a journal bearing in a rotor-bearing system where more realistic models are involved. The presented calculation method provides a basis for studying the nonlinear dynamic behavior of a general rotor-bearing system.

A general review of Computational Fluid Dynamics (CFD) applications in the automotive industry is presented. CFD has come a long way in influencing the design of automotive components due to continuing advances in computer hardware and software as well as advances in the numerical techniques to solve the equations of fluid flow. The automotive industry’s interest in CFD applications stems from its ability to improve automotive design and to reduce product cost and cycle time. We are able to utilize CFD more and more in day-to-day automotive design, and we can expect better conditions for CFD applications in the coming years. CFD applications in the automotive industry are as numerous as are the codes available for the purpose. Applications range from system level (e.g., exterior aerodynamics) to component level (e.g., disk brake cooling). The physics involved cover a wide range of flow regimes (i.e., incompressible, compressible, laminar, turbulent, unsteady, steady, subsonic and transonic flows). Most of the applications fall in the incompressible range and most are turbulent flows. Although most of the flows encountered are unsteady in nature, a majority of them can be approximated as steady cases. The challenge today is to be able to simulate accurately some very complex thermo-fluids phenomena, and to be able to get CFD results fast, in order to effectively apply them in the “dynamic” design environment of frequent design changes. The key is to utilize CFD in the early design phases so that design changes and fix-ups later are minimized. Proper use of CFD early, helps to significantly reduce prototyping needs and consequently, reduce cost and cycle time.

Combined Feature-Driven Richardson-Based Adaptive Mesh Refinement for Unsteady Vortical Flows

Computational Fluid Dynamics (CFD) applications in Floating Offshore Wind Turbine (FOWT) dynamics: A review

To evaluate the application of computational fluid dynamics (CFD) on a patient-specific hemodynamic model of aortic arch. The original Dicom format image data of a patient were acquired by computed tomographic angiography (CTA). A 3-dimensional (3D) model based on CFD was constructed through the right amount of boundary conditions and hemodynamic parameters related with flow velocity, shear force and wall stress on lumen were analyzed accordingly. The 3D model based on CFD could reflect the characteristic of flow velocity, shear force and wall stress on lumen in vitro. (1) The distributions of hemodynamic variables during cardiac cycle were spatiotemporally different. The unidirectional high-speed systolic current was replaced by diastolic eddy current and reversed flow. The distribution of flow velocity and shear stress gradually increased from outer wall of aortic artery to inner wall under the influences of such anatomical factors as vascular branching and distortions of descending aorta; (2) the magnitude and volatility of wall stress in ascending aorta were greater than those of aortic arch and descending aorta, but the least results were at the lateral wall of descending aorta area. In addition, the wall stress of external wall was higher than the lateral wall in the same section. The hemodynamic research of aortic arch based on CFD may actually simulate the characteristics of blood flow and wall stress so as to become a new reliable and convenient application tool in etiological diagnosis and surgical planning.

Aortic dissection is a life-threatening disease with acute onset,rapid progression and high mortality.Hemodynamic factors have important reference value in the development and treatment of aortic dissection.Computational fluid dynamics can intuitively and visually simulate the hemodynamic state of human blood vessels and quantify it numerically.However,computational fluid dynamics without fluid-structure interaction analysis cannot reflect the real situation of the human body.Therefore,the fluid-structure interaction numerical simulation of aortic dissection is worthy of further study to achieve more accurate evaluation of hemodynamic state,postoperative effect and risk prediction.In this paper,the application and research progress of computational fluid dynamics based on fluid-structure interaction technology in aortic dissection are briefly reviewed.

This erratum corrects errors that appeared in the paper “A Hydrofoil Configuration for Wind Powered Energy Ship Applications” which was published in Proceedings of the ASME 2017 Fluids Engineering Division Summer Meeting, Volume 1B, Symposia: Fluid Measurement and Instrumentation; Fluid Dynamics of Wind Energy; Renewable and Sustainable Energy Conversion; Energy and Process Engineering; Microfluidics and Nanofluidics; Development and Applications in Computational Fluid Dynamics; DNS/LES and Hybrid RANS/LES Methods, V01BT07A003, July 2017, FEDSM2017-69402, doi: 10.1115/FEDSM2017-69402.

Calibrations and validations of Computational Fluid Dynamics (CFD) applications are significantly time-consuming. To reduce the execution time of the CFD applications, parallel-computing approach is often employed. In addition, high performance computing systems and cloud computing solutions are also appropriate tools to the CFD applications. One of the challenging problems is to schedule tasks on virtualized machines of the cloud-based high performance systems. Instead of employing an adaptive algorithm to cope with the uncertainty of the virtualized resources, in this study, we propose an idea to predict the execution time of Telemac-2D, which is a CFD application. The predicted execution time is very essential in all scheduling algorithms. The application is executed several times with different settings of model’s parameters and allocated resources to produce an experimental dataset. The dataset is then used to predict the execution time of the application by utilizing a machine learning-based approach. The predictive model consists of two steps that classify and predict the execution. The C4.5 algorithm is used to classify the execution ending status whereas Multi-layer Perceptron (MLP) and a mixture of MLPs (MiMLP) are used to predict the execution time. The experiments indicate that the predictive model is appropriate to predict the execution of the Telemac-2D application since the accuracy of the C4.5 algorithm is 100 % and R and MARE of MiMLP are 0.957 and 17.090, respectively.

Computational fluid dynamics (CFD) applications are highly demanding for parallel computing. Many such applications have been shifted from expensive MPP boxes to cost-effective clusters. Auto-CFD is a pre-compiler which transforms Fortran CFD sequential programs to efficient message-passing parallel programs running on clusters. Our work has the following three unique contributions. First, this pre-compiler is highly automatic, requiring a minimum number of user directives for parallelization. Second, we have applied a dependency analysis technique for the CFD applications, called analysis after partitioning. We propose a mirror-image decomposition technique to parallelize self-dependent field loops that are hard to parallelize by existing methods. Finally, traditional optimizations of communication focus on eliminating redundant synchronizations. We have developed an optimization scheme which combines all the non-redundant synchronizations in CFD programs to further reduce the communication overhead. The auto-CFD has been implemented on clusters and has been successfully used for automatically parallelizing structured CFD application programs. Our experiments show its effectiveness and scalability for parallelizing large CFD applications.

This paper comparatively evaluates the microarchitectural performance of two representative Computational Fluid Dynamics (CFD) applications on the Intel Many Integrated Core (MIC) product, the Inte...

Research Article| February 01 2009 The practical application of computational fluid dynamics to dissolved air flotation, water treatment plant operation, design and development Tony Amato; Tony Amato 1Enpure Ltd, Enpure House, Woodgate Business Park, Kettleswood Drive, Birmingham, B323DB, UK E-mail: tamato@enpure.co.uk E-mail: tamato@enpure.co.uk Search for other works by this author on: This Site PubMed Google Scholar Jim Wicks Jim Wicks 2The Fluid Group, Magdalen Centre, The Oxford Science Park, Oxford, OX44GA, UK E-mail: jim.wicks@thefluidgroup.com Search for other works by this author on: This Site PubMed Google Scholar Journal of Water Supply: Research and Technology-Aqua (2009) 58 (1): 65–73. https://doi.org/10.2166/aqua.2009.003 Article history Received: January 21 2008 Accepted: April 10 2008 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Cite Icon Cite Permissions Search Site Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsThis Journal Search Advanced Search Citation Tony Amato, Jim Wicks; The practical application of computational fluid dynamics to dissolved air flotation, water treatment plant operation, design and development. Journal of Water Supply: Research and Technology-Aqua 1 February 2009; 58 (1): 65–73. doi: https://doi.org/10.2166/aqua.2009.003 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Computational fluid dynamics (CFD) can be applied to the advancement of dissolved air flotation (DAF) plant design. The use of CFD in design and predictive analysis, in particular here with reference to the upgrading of an existing DAF plant from 30 to 60 Ml/d and associated diagnostics, while still developing, helped by the emergence of ever more powerful computational systems, can be regarded as an established tool providing beneficial and useful data, although on occasions care may be required in the interpretation of results. The initial CFD studies were undertaken using the existing and upgraded works flows and structures at both ‘low’ and ‘high’ temperatures, i.e. 2 and 20°C, while the modelling results are reported using graphical representations of ‘contours of flow velocity’ and ‘velocity vectors’. In addition the degree of short circuiting based on T10 together with other retention parameters T50 and T50/m are reported. Further modifications were also considered: how changes to the incline baffle and tank depth can impact on the predicted distribution, vorticity and in practice on the actual subnatant water quality measured in terms of turbidity. Finally applying CFD to DAF plant design is shown to be a beneficial tool for the designer. computational fluid dynamics, dissolved air flotation, water treatment This content is only available as a PDF. © IWA Publishing 2009 You do not currently have access to this content.