جستجوی مقالات مرتبط با کلیدواژه « اپن فوم » در نشریات گروه « مکانیک »

The present paper introduces the implementation of a concurrent solver for pressure and velocity to solve free surface flows within the foam-extend framework. Integrating pressure and velocity fields with interface tracking algorithm has led to the development of a solver equivalent to the base foam-extend solver, named interTrackFoam. The current algorithm is entirely implemented using the structures, classes, and functions available in the foam-extend framework, and all the capabilities of this framework remain usable. Additionally, this solver utilizes libraries related to block matrices in foam-extend along with parallel solving capabilities. The block matrix system serves as the foundation for the concurrent solver. Notably, reducing the number of inner loops and performing one-step pressure and velocity solving are among the primary differences from the recognized default solver. Essentially, this solver represents the initial step towards a concurrent solver for velocity, pressure, temperature, and constituents with heat and mass transfer capabilities. The solver's capability is demonstrated through solving various experimental cases, including three-dimensional reservoirs, free surface flow around airfoils, and flow over sloping surfaces. With the concurrent solving capability of pressure and velocity, this solver holds significant potential in addressing complex physics and geometries. The ability for simultaneous solving enables reducing iterations or considering relatively higher time steps for flow computation.

Numerical methods as one of the subcategories of theoretical models can predict the behavior of energetic materials with appropriate accuracy and away of experimental tests limitations. In this investigation, computational fluid dynamics tool has been used to predict the blast wave propagation with Consideration of geometrical obstacles. Two solvers (extendedSonicFoam and blastFoam) from the open source technology module, OpenFOAM  have been used for simulations and To enhance confirmation with reality, large eddy simulation method was employed for turbulence modeling. In addition to the ideal gas equation of state (EOS), the BKW EOS, which is a complete EOS with an explicit temperature dependence, have been used to correlate the various thermodynamic parameters. Several gauges were positioned to record the pressure-time signals and the experimental data reported in the resources were used for validation. It should be noted that the maximum error of simulations was 12.29% for different blast wave parameters. deviation from standard for ideal gas numerical results was greater than that of real gas assumption and blastFoam solver has been predicted maximum positive phase overpressure, arrival time and positive phase impulse, which are the important parameters of blast wave, with less error in comparison to extendedSonicFoam solver.

The placement of a pier causes a three-dimensional complex flow pattern around the pier, which lead to scouring hole around the pier. In this research, modeling of scouring around piers was performed both experimentally and numerically using pimpleLPTdensFoam solver in OpenFOAM. In the first section, two different scenarios were used to simulate the scouring process. In the two numerical models, the effect of phase coupling and drag models on the scoured bed was investigated. One-way coupling with sphere drag model was implemented in the first scenario and four-way coupling with nonsphere drag model in the second one. According to the results, the first model was not satisfying, but the result of the second model was in good agreement with experimental results. The maximum depth of scour at the cross-section in numerical and experimental results was equal (6 percent error). All the simulations were done using the Euler-Lagrange approach and k-w turbulence model to simulate turbulent flow. In the second section of this research, to investigate effective parameters on the reduction of scour, three numerical models including a simple cylindrical pier and two more models using pier with collar were simulated. In order to study the effect of a collar on the reduction of scouring, the simple cylinder without a collar and then with the presence of collar at two different levels were performed. The results show that using collar in level 3.5 and level 4 may respectively lead to 49.2 and 29.7 percent reduction in maximum depth of scour.

In the present study, the effects of several global chemical kinetics in 3-dimensional numerical simulation of methane combustion in a horizontal combustion chamber which has lifted flame by a set of open source code OpenFOAM, is compared. The purpose of this comparison is to study the effects of 1, 2 and 4 step global kinetics on velocity, temperature and species distribution. In this simulation, conservation and state equations are solved simultaneously. Partial differential equations are discreted by finite volume method. The effects of turbulence by standard k-e, radiation by P1 model and turbulence-combustion interaction by PaSR are modeled. The results of numerical simulations have been validated by a cylindrical combustion chamber experimental data. The results show that the kinetics have considerable differences in results of velocity, temperature and species in the final third of the chamber where the flame is located, and differently predict locations of the flame. According to these results, 4-step mechanisms were more accurate than the 2-step type. Between 4 step mechanisms, JL is more accurate than Kim in overall; However, its calculation time is higher than the Kim. Single step kinetics were not able to keep the lifted flame.Towards the experimental results, 2-step model predicts the flame in downward and Kim mechanism estimates the flame in the upward.

Conjugate heat transfer is one of the most important aspects of energy conversion and plays an important role in the thermal efficiency and fuel consumption of chambers. In the present work, a two-dimensional model for reacting flow is presented to calculate transport equations of mass, momentum, energy and species. A new solver is developed for the open-source OpenFOAM software. This new solver is able to predict the conjugate heat transfer effects of reactions and transport processes in fluid and heat conduction in solid as well as radiation in surrounding surface. The coupled method is used and the continuity of temperature and heat flux on the fluid and solid interface is applied in order to analyze conjugate heat transfer through boundary conditions. Experimental data of honeycomb burner is used to validate the new solver. Numerical results are in a good agreement with experimental data. The results show that change of fluid inlet condition and geometry dimensions affect the interaction of conjugate heat transfer and location of released heat of combustion. The location of flame is moved toward outlet as the inlet velocity is increased and toward inlet as the equilibrium ratio is increased. Increasing the length and thickness of solid reduces the preheat area as well.

The fThe flow field around the axisymmtric stream lined bodis which forms the main body of the airplaines and submarines has been the subject of several researches. Turning maneuvers of submarines result in cross flow separation that generates large hydrodynamic forces. The separation of a simple axisymmetric body is very complex in nature. Understanding these vortical flows is paramount to improving vehicle performance and design. A suitable way to reduce the effects of this separated flow is to use vortex generators. The main goal of the present study is to investigate the flow field around a Suboff standard underwater model employing the vortex generator by using the oil flow visualization method and CFD method (OpenFOAM code) at 0° ≤ α ≤ 30° angles of attack. The novelty of the this study is the application of oil flow visualizing method and CFD simulation which can help us to precisely study the structure of three-dimensional vortical flow field. The results show that Vortex Generators placed along the submarine do indeed significantly reduce cross flow separation, size of vortices and drag forces.

The present paper investigated the capability of various non-linear k–ε models for predicting flow field and pollutant dispersion around a cubical model building with a stack vent located on its roof center within the turbulent boundary layer. One quadratic model proposed by Nisizima and Yoshizawa, and two cubic models, proposed by Lien et al. and Ehrhard and Moussiopoulos were examined by comparing their simulation results with the wind tunnel data and standard k–ε model. All the computations were performed by using the self-developed object-oriented C++ programming in OpenFOAM CFD package, which contains applications and utilities for finite volume solvers. The standard k–ε model provided inadequate results for the flow field, because it could not reproduce the basic flow structures, such as reverse flow on the roof. By contrast, the non-linear models were able to predict anisotropic stresses and correctly showed the dominant stress over the roof to be the streamwise Reynolds stress. The non-linear models were able to predict the concentration field better than the SKE model due to inclusion of the quadratic and cubic terms. Among the RANS models, the Ehrhard model showed the best agreement with the experimental data. It was shown that concentrations predicted by all turbulence models were less diffusive than those of the experiment, although the non-linear k–ε models have reduced this difference.