turbulence models in computational fluid dynamics (CFD) aim to capture a complex phenomenon through simplified mathematical models. The models themselves range in terms of application, complexity and methodology. This work looked at a Transitional model for Reynolds averaged Navier Stokes equations. In particular the focus was on the correlation based intermittency and momentum thickness Reynolds number (γ-R̃ eθ t) model. The original model has high order correlations, that were determined and calibrated from flat plate tests of various pressure gradients. In this work the correlations were simplified to reduce the number of calibration coefficients and help in understanding the effect of each parameter. Flat plate test data, from the European Research Community on Flow, turbulence and Combustion (ERCOFTAC) T3A series, were used to verify the lower order approximations through OpenFOAM simulations. The open source CFD package OpenFOAM was used for its easy access to the base code. The reduced order model was then applied to a National Advisory Committee for Aeronautics (NACA) 0012 foil at a Transitional Reynolds number of 360 000 as a means of validation. The reduced order, the original γ-R̃ eθ t and the fully turbulent k-omega shear stress transport (k − ω SST) turbulence models are compared over a range of angles of attack to highlight the difference between models. The proposed model reduced the runtime of simulation by approximately 6%. The reduction in model coefficients meant a step by step adjustment could be implemented to increase model accuracy. In addition the adjusted model increased the accuracy of drag prediction on a NACA0012 airfoil, while maintaining a similar lift prediction as the original.

The Middle East today can be considered an area with the features of chaos due to its geopolitical structure, complex historical identity and decades of crisis. In this volatile area, security has undergone an extensive alteration, and the Islamic Republic of Iran, as a major actor and historical activist, needs certain behavioral patterns to correspond to the situations and trends of security chaos. The present paper seeks to identify the elements of Iran's regional behavioral patterns in the Middle East security chaos. It is hypothesized that Iran needs to take advantage of patterns of constructive interaction, balancing, geopolitical stability, and Interactive Order-Building to play a regional role in this chaos. A descriptive-analytical method and theoretical modeling is employed to account for the historical process of chaos in the Middle East and Iran's chaos management model in foreign policy.

The deposition behavior of fine sediment is an important phenomenon, and yet unclear to engineers concerned about reservoir sedimentation. An elliptic relaxation turbulence model (`V2 ¦ model) has been used to simulate the motion of turbid density currents laden with fine solid particles. During the last few years, the `V2 ¦ turbulence model has become increasingly popular due to its ability to account for near-wall damping without use of damping functions. The `V2 ¦ model has also proved to be superior to other RANS (Reynolds-Averaged Navier-Stokes) methods in many fluid flows where complex flow features are present. This current becomes turbulent at low Reynolds number (order 1000). The k-e model, which was standardized for high Reynolds number and isotropic turbulence flow, cannot simulate the anisotropy and nonhomogenous behavior near the wall. In this study, the turbidity current with a uniform velocity and concentration enters the channel via a sluice gate into a lighter ambient fluid and moves forward down-slope. The model has been validated by available experimental data sets. Moreover, results have been compared with the standard k-e turbulence model. The deposition of particles and the effects of their fall velocity on concentration distribution, Richardson number, and the deposition rate are also investigated. The results show that the coarse particles settle rapidly and make the deposition rate higher.

Prediction of flow behavior in the transition region is the key issue in many scientific problems. Many attempts have been made by researchers to propose and modify the models estimating the flow behavior in this region. In these flows, the governing equations, including the continuity, the Navier-Stokes, and the transmittance along with the Shear Stress Transport models are solved simultaneously to predict the flow behavior. There are several coefficients in the governing equations which affect the flow simulation. In this study, the Transitional shear stress transport model is modified by altering two coefficients in the intermittency equation. A combination of these coefficients is implemented, and the effects are studied. To assess the accuracy of the proposed coefficients in simulation, they are applied to three individual internal flows, including a smooth axisymmetric pipe, two parallel plates, and a backward-facing step. Different variables such as the friction factor coefficient, fully developed friction factor, and the reattachment length are explored. A comparison between the results and both analytical and experimental data confirms a good accuracy in the predictions. Furthermore, using the presented models the entrance length is well predicted in turbulent and Transitional flows.

turbulence in the spacecraft tanks has undesirable effects during maneuvers. Therefore, considering the importance of the correct orbit maneuver to reach the target orbit, it is necessary to model and select a proper method to control it before performing the orbital maneuvers. In this paper, by using a new method for modeling turbulence in reservoirs and for the first time, spacecraft attitude control and turbulence control are simulated using this model. Fuel turbulence is modeled using a moving pulsed ball model, and the whole system's dynamic equations are derived using Krishehoff equations. The maneuver of the spacecraft and the motion of the moving pulsed ball is considered in the plane; therefore, the spacecraft and pulsed ball system will have four degrees of freedom. simulation results show successful modeling and simultaneous control of turbulence and situation

The dispersion of hazardous gas in the environment presents dangerous risks for people living close to chemical plants or storages. Since heavy gases tend to stay at lower levels and disperse at a slower pace in the atmosphere, they are potentially more dangerous. In this paper, various mathematical models for turbulence (including k-ε , RNG k-ε , EARSM, LES, DES) and their associated parameters have been assessed, compared and validated against the experimental data in various scenarios to find the most suitable one for atmospheric dispersion of dense-gases. This topic has been investigated and validated by a computational fluid dynamics (CFD) simulation of the Kit-Fox experiment. The precision of the CAD models, practicality, computational resource requirements, and some other factors have been considered and addressed in this paper to achieve a comprehensive solution for atmospheric dispersion. The results here suggest that the proper selection of the turbulence model and the turbulent Schmidt number is crucial. Our results indicate that the most promising combination in the case of atmospheric dense-gas dispersion is the RNG k-ε model with the Schmidt number of 0. 4, considering the demand for accuracy and computational resource.

Transitional justice refers to the ways of addressing the large scale or systematic Human and Humanitarian Rights violations in periods of transition from conflict and repression, that the normal system of criminal justice, due to the extent and severity of violations, is not able to provide them adequate and appropriate response. The mechanisms of Transitional justice are different, depending on the circumstances prevailing in the Transitional society. Transitional justice, is useing in different societies as a way to confront the legacies of oppression, war and violence. This, is accomplishing through mechanisms like criminal prosecution, truth-seeking, reparation, and institutional reforms. This paper, along with the conceptualization of Transitional justice and the introduction of its various criminal and non-criminal mechanisms during the transition period, examines the acceptability of these mechanisms in Transitional societies and their validity in terms of International Criminal Court.