The influence of computational domain discretization on CFD results concerning aerodynamics of a vehicle

The discretization of computational domain is a crucial step in Computational Fluid Dynamics (CFD) because it influences not only the numerical stability of the analysed model but also the agreement of obtained results and real data. Modelling flow in packed beds of granular materials is a very challenging task in terms of discretization due to the existence of narrow spaces between spherical granules contacting tangentially in a single point. Standard approach to this issue results in a low quality mesh and unreliable results in consequence. Therefore the common method is to reduce the diameter of the modelled granules in order to eliminate the single-point contact between the individual granules. The drawback of such method is the adulteration of flow and contact heat resistance among others. Therefore an innovative method is proposed in the paper: single-point contact is extended to a cylinder-shaped volume contact. Such approach eliminates the low quality mesh elements and simultaneously introduces only slight distortion to the flow as well as contact heat transfer. The performed analysis of numerous test cases prove the great potential of the proposed method of meshing the packed beds of granular materials.

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Numerical Analysis of Flow in Building Arrangement: Computational Domain Discretization

Applied Sciences ◽

10.3390/app9050941 ◽

2019 ◽

Vol 9 (5) ◽

pp. 941 ◽

Cited By ~ 6

Author(s):

Marcin Sosnowski ◽

Renata Gnatowska ◽

Karolina Grabowska ◽

Jarosław Krzywański ◽

Arkadiusz Jamrozik

Keyword(s):

Particle Image ◽

Numerical Models ◽

Rapid Development ◽

Real Data ◽

Computational Domain ◽

Time Cost ◽

Hexahedral Elements ◽

Image Velocimetry ◽

Computational Fluid Dynamics Cfd ◽

Domain Discretization

The progress in environmental investigations such as the analysis of building arrangements in an urban environment could not have been expanded without the use of computational fluid dynamics (CFD) as a research tool. The rapid development of numerical models results in improved correlations to results obtained with real data. Unfortunately, the computational domain discretization is a crucial step in CFD analysis which significantly influences the accuracy of the generated results. Hence an innovative approach to computational domain discretization using polyhedral elements is proposed. The results are compared to commonly applied tetrahedral and hexahedral elements as well as experimental results of particle image velocimetry (PIV). The performed research proves that the proposed method is promising as it allows for the reduction of both the numerical diffusion of the mesh as well as the time cost of preparing the model for calculation. In consequence, the presented approach allows for better results in less time.

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Application of the method of mathematical modeling for forecasting channel deformations at the underwater crossing of the main pipeline

SCIENCE & TECHNOLOGIES OIL AND OIL PRODUCTS PIPELINE TRANSPORTATION ◽

10.28999/2541-9595-2020-10-6-599-609 ◽

2020 ◽

Vol 10 (6) ◽

pp. 599-609

Author(s):

Valery А. Gruzdev ◽

◽

Georgy V. Mosolov ◽

Ekaterina A. Sabayda ◽

◽

...

Keyword(s):

Mathematical Modeling ◽

Mathematical Model ◽

Roughness Coefficient ◽

Computational Domain ◽

Channel Deformations ◽

Geological Surveys ◽

Kuban River ◽

The Stability ◽

Protective Structures

In order to determine the possibility of using the method of mathematical modeling for making long-term forecasts of channel deformations of trunk line underwater crossing (TLUC) through water obstacles, a methodology for performing and analyzing the results of mathematical modeling of channel deformations in the TLUC zone across the Kuban River is considered. Within the framework of the work, the following tasks were solved: 1) the format and composition of the initial data necessary for mathematical modeling were determined; 2) the procedure for assigning the boundaries of the computational domain of the model was considered, the computational domain was broken down into the computational grid, the zoning of the computational domain was performed by the value of the roughness coefficient; 3) the analysis of the results of modeling the water flow was carried out without taking the bottom deformations into account, as well as modeling the bottom deformations, the specifics of the verification and calibration calculations were determined to build a reliable mathematical model; 4) considered the possibility of using the method of mathematical modeling to check the stability of the bottom in the area of TLUC in the presence of man-made dumping or protective structure. It has been established that modeling the flow hydraulics and structure of currents, making short-term forecasts of local high-altitude reshaping of the bottom, determining the tendencies of erosion and accumulation of sediments upstream and downstream of protective structures are applicable for predicting channel deformations in the zone of the TLUC. In all these cases, it is mandatory to have materials from engineering-hydro-meteorological and engineering-geological surveys in an amount sufficient to compile a reliable mathematical model.

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Downscaled Finite Element Modeling of Metal Targets for Surface Roughness Level under Pulsed Laser Irradiation

Applied Sciences ◽

10.3390/app11031253 ◽

2021 ◽

Vol 11 (3) ◽

pp. 1253

Author(s):

Evaggelos Kaselouris ◽

Kyriaki Kosma ◽

Yannis Orphanos ◽

Alexandros Skoulakis ◽

Ioannis Fitilis ◽

...

Keyword(s):

Surface Roughness ◽

Finite Element ◽

Surface Acoustic Waves ◽

Pulsed Laser ◽

Multiscale Simulation ◽

Experimental Methodology ◽

Computational Domain ◽

Area Of Interest ◽

Depth Analysis ◽

Laser Solid Interactions

A three-dimensional, thermal-structural finite element model, originally developed for the study of laser–solid interactions and the generation and propagation of surface acoustic waves in the macroscopic level, was downscaled for the investigation of the surface roughness influence on pulsed laser–solid interactions. The dimensions of the computational domain were reduced to include the laser-heated area of interest. The initially flat surface was progressively downscaled to model the spatial roughness profile characteristics with increasing geometrical accuracy. Since we focused on the plastic and melting regimes, where structural changes occur in the submicrometer scale, the proposed downscaling approach allowed for their accurate positioning. Additionally, the multiscale simulation results were discussed in relation to experimental findings based on white light interferometry. The combination of this multiscale modeling approach with the experimental methodology presented in this study provides a multilevel scientific tool for an in-depth analysis of the influence of heat parameters on the surface roughness of solid materials and can be further extended to various laser–solid interaction applications.

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Effect of the Preheated Oxidizer Temperature on Soot Formation and Flame Structure in Turbulent Methane-Air Diffusion Flames at 1 and 3 atm: A CFD Investigation

Energies ◽

10.3390/en14123671 ◽

2021 ◽

Vol 14 (12) ◽

pp. 3671

Author(s):

Subrat Garnayak ◽

Subhankar Mohapatra ◽

Sukanta K. Dash ◽

Bok Jik Lee ◽

V. Mahendra Reddy

Keyword(s):

Mole Fraction ◽

Air Temperature ◽

Reaction Rate ◽

Volume Fraction ◽

Diffusion Flames ◽

Soot Formation ◽

Flame Structure ◽

Soot Volume Fraction ◽

Computational Domain ◽

Pressure Elevation

This article presents the results of computations on pilot-based turbulent methane/air co-flow diffusion flames under the influence of the preheated oxidizer temperature ranging from 293 to 723 K at two operating pressures of 1 and 3 atm. The focus is on investigating the soot formation and flame structure under the influence of both the preheated air and combustor pressure. The computations were conducted in a 2D axisymmetric computational domain by solving the Favre averaged governing equation using the finite volume-based CFD code Ansys Fluent 19.2. A steady laminar flamelet model in combination with GRI Mech 3.0 was considered for combustion modeling. A semi-empirical acetylene-based soot model proposed by Brookes and Moss was adopted to predict soot. A careful validation was initially carried out with the measurements by Brookes and Moss at 1 and 3 atm with the temperature of both fuel and air at 290 K before carrying out further simulation using preheated air. The results by the present computation demonstrated that the flame peak temperature increased with air temperature for both 1 and 3 atm, while it reduced with pressure elevation. The OH mole fraction, signifying reaction rate, increased with a rise in the oxidizer temperature at the two operating pressures of 1 and 3 atm. However, a reduced value of OH mole fraction was observed at 3 atm when compared with 1 atm. The soot volume fraction increased with air temperature as well as pressure. The reaction rate by soot surface growth, soot mass-nucleation, and soot-oxidation rate increased with an increase in both air temperature and pressure. Finally, the fuel consumption rate showed a decreasing trend with air temperature and an increasing trend with pressure elevation.

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