Turbulence models have long been developed and examined for their accuracy and stability in variety of environments. While many flows work with excited turbulence intensity, models have rarely been tested to explore whether their accuracy withstands with augmented free stream turbulence intensity or decline in reasonable solutions. In present study the turbulent intensity of the air, moving parallel to a flat plate is increased from 0.4 to 6.6% for the whole flow, downstream to the screen. Three popular turbulence models are examined by investigating the turbulence penetration into flow field as well as into turbulent boundary layers over the flat plate. Results of numerical solutions for Standard k-e, Realizable k-e and finally two equations Shear Stress Transport k-w model are compared to experimental measurements and results are discussed. Results of variation of free stream turbulence intensity from flow field out of boundary layer, in addition, streamwise mean velocity, streamwise rms velocity and skin friction coefficient from boundary layer are investigated. Conclusion is made that despite restrictions of these turbulent models specially in predicting flow near a turbulent/non-turbulent interface, they have acceptable performance in both low and high intensity turbulent flows.

This paper presents pore scale simulation of turbulent combustion of air/methane mixture in porous media to investigate the effects of multidimensionality and turbulence on the flame within pore scale. A porous medium consisting of a staggered arrangement of square cylinders considered here. Results of turbulent kinetic energy, temperature, flame thickness, flame structure and flame speed are presented and compared at different equivalence ratios. The turbulent kinetic energy increases along the burner because of turbulence created by the solid matrix with a sudden jump at the flame front due to increase of the velocity as a result of thermal expansion. Also, it is shown that at higher equivalence ratios, the effect of turbulence within porous burner is highly significant phenomenon. Due to higher turbulence effects in higher equivalence ratios, the flame thickness increases by increasing the equivalence ratio which is in opposite of the trend observed in laminar flow simulation. Also, it is shown that the dimensionless flame speed and excess temperature is higher at lower equivalence ratios due to lower heat loss to the cold upstream environment of burner. Two dimensional structure of flame in the pores of porous medium is shown in the present study via isotherm lines.

In this paper, linear accelerated turbulent pipe flow has been simulated at various Reynolds numbers using five common turbulence models. The models considered are the Baldwin-Lomax algebraic model, the Spalart-Allmaras one-equation model, theκ-e model with wall correction of Lam and Bremhorst, theκ-ω model and the κ-ε-ν2 model. The goal is to evaluate the performance and precision of these models for prediction of the wall shear stress, Reynolds stress, turbulence viscosity, delay time in response and mean velocity. Factors such as changes in pipe diameter, fluid type, initial Reynolds number of acceleration and rate of acceleration and its effect on the above parameters has examined carefully. In order to verify the results, the experimental and numerical results (turbulence modeling and Large Eddy Simulation) of other researchers have been compared with the present results. The results show the desired accuracy of the one-dimensional modeling of accelerated turbulent pipe flow in comparison with Large Eddy Simulation results (three-dimensional). The response of delay time, simulated by the models (except BL model) shows relatively good agreement with experimental data. Comparing the distribution of mean velocity, turbulent kinetic energy and turbulent viscosity shows  k-e-ν2 model leads to a better accuracy compared with the other models.

The study of flow in compound channels with vegetated floodplains is essential to assessing the development of the stage-discharge relationship and sediment and pollutant transport. The present study experimentally investigated mean flow and turbulence characteristics in a prismatic compound channel. The experimental program consisted of vegetated and non-vegetated floodplains with different relative depths. The results show that vegetation had a significant effect on the flow characteristics of streamwise, lateral, and vertical velocity and Reynolds stress. For a given relative depth, the conveyance capacity of the channel decreased up to 31% for a vegetated floodplain over a non-vegetated floodplain. Although, the depth-averaged velocity varied significantly across the main channel, it was fairly constant over the vegetated floodplain. Strong secondary currents and lateral momentum transfer between the main channel and its floodplain led to high gradients in the depth-averaged velocity, bed shear stress, and turbulent kinetic energy at the interface.

The remote leakage detection methods in pressurized pipes, are based on the analysis of the pressure fluctuations during the transient flow. In this regard, practical applications of transient flow can be improved and simultaneously, the destructive effects of transient flow on the pipeline and its equipment would be decreased by studying and understanding the transient flow. In the present paper, it has been tried to analyze the flow behavior and the turbulence parameters during different cycles by modeling transient flow with a leak in two dimensions. The proposed numerical model is based on the finite difference scheme and a flux-corrected transport method is used to eliminate numerical dispersion. In order to study the behavior of turbulence in the flow and its dissipation, the k- turbulence model is coupled with the 2D transient flow model and also the leak effect is added to the steady and unsteady parts of the model. In the presence of the leak in the transient flow, a considerable change is seen in the velocity profile and the turbulence parameters in the flow back and forward cycles. In the initial cycles of the transient flow, the different parameters in the upstream of the leak, decrease gradually and increase in the downstream of the leak until these two flows reach each other. Later, the turbulence initiates to extend from the near pipe wall into inner layers and the magnitude decreases gradually by passing time.

In this paper, inflow turbulence effects on the flow wake parameters around a NACA001 airfoil at zero incidence angle and Reynolds number of 38,700 were investigated. Various turbulence promoter networks were used to achieve turbulence intensity of 5% and 6%. Experiments have been conducted for three different turbulence intensities in which mean velocity parameters, turbulence intensity, frequency response, and Strouhal number were measured. Half of the wake width (b1/2) in all three cases of turbulence, was increased with increasing x/d and turbulence intensity. It was also found that vortex formation length is decreased with turbulence intensity. Besides, it became clear that Strouhal number is reduced with any increase in turbulence intensity or in the distance from the trailing edge of the airfoil.

Orifices are one of the common flowmeter for fluid flow measurement in industrial piping. Selection the suitable turbulence model has very important to achieve good accuracy of flow measuring in numerical simulation. This paper describes numerical simulation of the flow through a circular orifice in pipe by using computational fluid dynamics (CFD) with various turbulence modeling. Therefore the orifice in pipe is simulated in Ansys CFX 15 on 3D mode and different turbulence models such as standard 𝑘 − 𝜀 , 𝐵 𝑆 𝐿 , 𝑆 𝑆 𝑇 and 𝐵 𝑆 𝐿 𝑅 𝑆 𝑀 are employed. Via comparison of these results with experimental data and some valid numerical results, it can be found that the standard 𝑘 − 𝜀 model is the best agreement with experimental data. Also discharge coefficient of orifice is compared with standards ISO 5167 and ASME with about five percent error. In this model, maximum velocity is occurred downstream of orifice at distance of nearly one-time diameter of orifice hole. In this section the velocity of fluid is more than four times of the velocity at inlet the pipe.