A Scalable Infrastructure for Online Performance Analysis on CFD Application

The computational fluid dynamics (CFD) grid application platform provides a grid environment for CFD applications using high performance computing. It adopts service oriented architecture (SOA), is based on IBM's Service Domain, extends and customizes it for CFD applications in several modules, such as service requesting, job scheduling, job management, failure recovery, etc. By defining general CFD application interfaces such as data format, the platform integrates different CFD applications, including mesh generation, domain decomposition and resolvers, to follow the workflow customized by end-users to finish a complete CFD job. Furthermore, CFD application development specifications and packages are provided to facilitate migrating most sequential and parallel CFD applications to the platform. Currently, a prototype system is available online to the public for testing.

This paper gives a discussion on the Computational Fluid Dynamics (CFD) applications in offshore engineering. Accurate hydrodynamic quantities are essential for engineering design. Offshore structures are generally subject to high Reynolds number flows. These high Reynolds number flow conditions (Re > 106 ) are difficult and expensive to achieve in an experimental setup. Therefore, it is attractive to use CFD to provide the essential hydrodynamic quantities for practical design. Verification and validation studies are important for determining the validity of the CFD prediction. A procedure of performing CFD simulation is shown. Different types of turbulence modelling are discussed. Three examples of high Reynolds number CFD simulations, covering flow around offshore structural components and waves past partially-submerged horizontal cylinders, are shown and discussed.

Computational Fluid Dynamics (CFD) is an important research field with a broad spectrum, requiring a close interplay between mathematical modeling, numerical methods, software development, and high performance computing. Programming CFD applications is an inherently difficult task due to many factors related to numerics and software. For modern CFD applications, use of parallel computers is a must, which makes the CFD code development even more challenging. Rapid and flexible programming of a parallel CFD application calls for re-usable serial and parallel software components plus a modular overall parallel framework that allows an easy coupling between different components. Moreover, more attention needs to be put on securing the performance of the software components. This minisymposium thus attempts to shed some light into the recent developments in respect of CFD-related numerical methods, programming techniques and software libraries.

Preconditioned Krylov subspace methods for solving nonsymmetric matrices from CFD applications

The application of computational fluid dynamics(CFD) in the food industry such as drying, thermal sterilization, mixing, refrigeration and humidification of cold storage was reviewed. The results from previous studies have shown that CFD was a powerful numerical tool that is applied to model fluid flow situations and aid in the optimal design of engineering equipment and food process. With the development of computer technology, it is conceivable that CFD will continue to provide more explanations for physical modeling of fluid flow and process system design for the food industry.

Root canal irrigation is an important step in root canal preparation procedures and has a great impact on the success rate of root canal treatment. Computational fluid dynamics (CFD) is a new method to study root canal irrigation. It can be used to simulate and visualize the process of root canal irrigation, and quantitatively evaluate the effect of root canal irrigation through parameters such as flow velocity and wall shear stress. In recent years, researchers have conducted extensive studies on the factors that influence root canal irrigation efficiency, such as the position of the irrigation needle, the size of root canal preparation, the types of irrigation needles, and so on. This article reviewed the development of root canal irrigation research methods, the steps of CFD simulation in root canal irrigation, and the application of CFD in root canal irrigation in recent years. It aimed to provide new research ideas for the application of CFD to root canal irrigation and to provide a reference for the clinical application of CFD simulation results.

Computational fluid dynamics

<div class="htmlview paragraph">Development of Caterpillar Fuel Systems' MEUI-B injector has involved application of Computational Fluid Dynamics (CFD) in order to improve performance of the high pressure spill valve. Initial performance bench testing with concept stage experimental injectors indicated that the chamber pressure was decaying at an unacceptably slow rate, and the valve demonstrated erratic behavior at some operating conditions. The slow pressure decay and inconsistent spill valve motion were believed to be caused by flow forces generated during the low lift portion of the spill valve opening event. This theory was pursued by utilizing CFD to design two valves for testing in the next phase of the injector development cycle: A baseline geometry, similar to the original concept injector valve, and a new design incorporating localized seat geometry changes for inducing flow force assisted valve opening. Bench test performance data clearly shows that the modified design significantly improves the spill valve opening event and subsequent chamber pressure decay rate. This paper documents the CFD analysis which led to the development of the new MEUI-B high pressure spill valve design.</div>

Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical analysis and data structures to calculate, analyze, and visualize fluid (liquids, gases, and dissolved gases) flows. This document provides general introductions to best practices for CFD modeling in water infrastructure for practitioners, particularly those new to CFD modeling, which is becoming a widely used tool in the design and retrofitting of water, wastewater, and stormwater infrastructure. The method serves as an alternative, or complement, to physical modeling. In recent years, CFD has often been used in evaluating and troubleshooting existing water systems as well as improving future designs. As with the applications in other fields, the popularity of CFD in the water industry has been propelled by a multitude of factors including, but not limited to, the maturity achieved by CFD techniques, the development of stable and reliable numerical schemes, and the ever-improving computer-aided design (CAD) and meshing technologies for real-world complex geometries. This has been accompanied by many commercial and open-source CFD packages that can be run on increasingly more powerful computing hardware. Despite the visible progress in the application of CFD in water infrastructure projects achieved to date, there are still many challenges that hinder the widespread use of CFD techniques in water treatment design. Perhaps more important is that many of these challenges may result in misuse of the tool with dire consequences. It is imperative that CFD practitioners appropriately apply this tool without overpromising capability or accuracy and that reviewers of CFD model results know what to look for in ensuring proper methods have been applied and that results are representative of reality.

SUMMARY Research background: Drying is one of the most traditional processes of food preservation. Optimizing the process can result in a competitive product on the market regarding its price and quality. A common method in use as a pretreatment to drying is ultrasound. The goal of this work is to analyze different drying methods with and without applying ultrasound (US) pretreatment, on heat and mass transfer, simulating numerically the temperature profile by computational fluid dynamics (CFD). Experimental approach: The melon slices were pretreated with ultrasound for 10 (US10), 20 (US20) and 30 (US30) min at 25 kHz, and the water loss and solid gain were evaluated. Samples were dried at different temperatures (50, 60 and 70 °C). The effective diffusivity was estimated, and experimental data were modelled using empirical models. The airflow in the dryer and the temperature profile in the melon slice were simulated via computational fluid dynamics (CFD). Results and conclusions: Ultrasound pretreatment reduced the drying time from 25% (samples US20 and US30 at 50 °C) to 40% (samples US20 and US30 at 70 °C). The two-term exponential model presented the best fit to the experimental data, and the diffusivity coefficients showed a tendency to increase as the time of exposure of the melon to ultrasonic waves increased. Pretreatment water loss and solid gain behaviour and drying kinetic and diffusion data were used to choose the best experimental conditions to be simulated with CFD. The heat transfer modelling through CFD showed that the temperature distribution along the melon slice was representative. Therefore, the profile obtained via CFD satisfactorily describes the drying process. Novelty and scientific contribution: The use of simulation tools in real processes allows the monitoring and improvement of existing technologies, such as food drying processes, that involve complex mechanisms, making it difficult to obtain some data. Application of CFD in the drying processes of fruits and vegetables is still very recent, being a field little explored. There is no record in the literature that uses CFD in the drying of melon.

Computational fluid dynamics (CFD) techniques have become an important tool for investigating and predicting flow behavior in many industrial and engineering processes. In the last two decades, CFD has been used for the study, design, and improvement of irrigation equipment. Numerical simulations can be used to predict fluid flow, heat transfer, and chemical reactions within complex systems. The objective of this review is to provide an overview of the uses of CFD in irrigation engineering applications. The paper is organized into two main sections: fundamentals of CFD and irrigation engineering applications. The first section presents the main methods used in numerical simulations, basic equations to predict fluid flow parameters, meshing concerns, and convergence criteria. In the second section, we present applications related to friction and local head losses in pipes, liquid and solid-liquid flow simulation in drippers, chemical scaling, filters, sprinklers, direct-acting pressure-regulating valves, and Venturi injectors. The briefly described applications indicated that CFD modeling can be an accurate, quick, and feasible method for the investigation of flow parameters in irrigation pipes, fittings, emitters, and accessories. The CFD simulations can be useful for designing new products as well as for improving and optimizing existing products. Computational fluid dynamics uses in irrigation engineering must be encouraged, particularly for innovation purposes resulting from the cooperation between academia and irrigation companies.

Perforate-Wash-Cement (P/W/C) is a well plugging technique extensively used by ConocoPhillips in the Greater Ekofisk Area over the last ten years. In Jet-type P/W/C, Tubing Conveyed Perforating (TCP) guns perforate casing in the target interval before the zone is washed and a cross-sectional cement plug is installed using a specialized Bottom Hole Assembly (BHA). The goal is to maximize the cement plug quality through optimizing the BHA and operational process parameters within constraints imposed by the operating conditions. This paper describes application of Computational Fluid Dynamics (CFD) to achieve this objective. CFD is well suited for modeling wash and cement processes including the associated non-Newtonian fluids. A CFD model of these processes employs unsteady multiphase Reynolds Averaged Navier Stokes (RANS) based Volume of Fluid (VOF) approach with a Shear Stress Transport (SST) K-omega turbulence model. BHA translation and rotation are simulated using moving deforming-layering mesh with interface approach. Physical properties of non-Newtonian fluids selected are based on in-situ conditions and derived via lab tests. CFD-specific considerations such as domain size, turbulence model, mesh type and size, and computational timestep are discussed in this paper. The magnitude and duration of the jet-induced "pressure pulse" in the annular space between the formation wall and the casing are a key to efficient displacement during the wash and cementing processes. Displacement efficiency, in terms of the percentage of mud or cement in a control volume as a function of time, depends on perforation size and density, nozzle size/number, flow rate, fluid properties, as the ROP/BHA pulling speed and tool RPM. Key findings from a parametric study to optimize these parameters are presented. To validate CFD nozzle flow predictions and to rule out potential for false results due to cavitation, laboratory tests were performed under pressurized conditions. A comparison of results from CFD simulations using traditional versus optimized parameters are presented, demonstrating significant efficiency improvement achieved. The study initially focused on North Sea application. Encouraged by substantial improvement in process efficiency through parametric optimization, the technique was extended to UK operations and is planned for the Bayu-Undan field. Cementing simulation results for Bayu-Undan specific well configurations are presented, showing how CFD modeling helped reveal less than ideal cementing efficiency. Ultimately, this work provides significant time savings and quality improvement for P&A projects while maintaining a high safety standard.

This paper reports the development of a computational fluid dynamics (CFD) model of a spark ignition (SI) engine and the application of the engine model into an undergraduate internal combustion (IC) course. This two-dimensional (2D) four-stroke SI engine model simulates the combustion of the fuel, heptane, in the engine cylinder based on realistic boundary conditions. The development of the model helps engineering students better understand the combined effects of chemical reactions, species transport, flow patterns and temperature distributions in the SI engine. This model has been applied in a practical session in an undergraduate engineering course since 2012. To the best knowledge of the authors, this is the first time that CFD engine models are used as a hands-on tool in IC engine courses. Feedback from students is quite positive.

Over the past several decades, the meanline analysis method based on the conventional empirical loss correlations, assuming that the flow characteristics averaged over the crosssection of flow passage could represent the three-dimensional flow phenomena through the passage of turbomachinery, has been widely employed to determine the overall geometric design variables for each component of turbomachinery and to predict the on and off-design performance characteristics. With the relentless increase in computing power, however, the computational fluid dynamics (CFD) techniques have remarkably progressed in the last decade, and CFD becomes commonly used not only as a design tool to improve the flow dynamic performance of specific components of turbomachinery but also as a virtual test rig to numerically experiment on a working prototype of the new/existing model. This Chapter demonstrates how the meanline and CFD analyses can be applied to carrying out the hydraulic design optimization and performance analysis of a mixed-flow pump with the non-dimensional specific-speed (Ns) of 2.44. Although the present article focuses on the incompressible flow machine, which falls into the regime of mixed-flow pumps with the non-dimensional specific-speed in the range of 1.9 to 2.5, the following procedure presented herein can be used efficiently as a practical design and analysis guide for general purpose turbomachinery.

Chapter 10 - Computational Fluid Dynamics