Evaluation and improvements of RANS turbulence models for linear diffuser flows

Heschl, Christian; Inthavong, Kiao; Sanz, Wolfgang; Tu, Jiyuan

doi:10.1016/j.compfluid.2012.10.015

Cited by 34 publications

(18 citation statements)

References 22 publications

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“…To improve flow predictions in RANS models, nonlinear eddy viscosity turbulence models were developed calibrated to the normal stresses (Heschl et al, 2013(Heschl et al, , 2014. The calibration ensured the log-law, and shear-layer behaviour was correct.…”

Section: Indoor Inhalation Exposurementioning

confidence: 99%

“…3). The 2 -v f model (Zhang and Chen, 2009;Li and Gong, 2012;Heschl et al, 2013) has been popular, among the RSM and LES methods (Liu and Novoselac, 2014) as alternatives to indoor airflow modelling to serve as work arounds to resolve the strong anisotropic behaviour in the near-wall region. Recently the continuous random walk model has been applied to include the effect of turbulent fluctuations on particle trajectories which is based on the normalized Langevin equation (Dehbi, 2011;Ghahramani et al, 2014).…”

Section: Indoor Inhalation Exposurementioning

confidence: 99%

See 1 more Smart Citation

From indoor exposure to inhaled particle deposition: A multiphase journey of inhaled particles

Inthavong

2019

Exp. Comput. Multiph. Flow

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Indoor air quality and its effect on respiratory health are reliant on understanding the level of inhalation exposure, particle inhalability, and particle deposition in the respiratory airway. In the indoor environment, controlling airflow through different ventilation systems can reduce inhalation exposure. This produces a wide variety of complex flow phenomena, such as recirculation, coanda flow, separation, and reattachment. Airborne particles drifting through the air, that move within the breathing region become inhaled into nasal cavity the nostrils. Studies have developed the aspiration efficiency to assist in predicting the fraction of inhaled particles. Inside the nasal cavity, micron and submicron particle deposition occurs in very different ways (inertial impaction, sedimentation, diffusion) and different locations. In addition, fibrous particles such as asbestos are influenced by tumbling effects and its deposition mechanism can include interception. Indoor fluid-particle dynamics related to inhalation exposure and eventual deposition in the respiratory airway is presented. This study involves multidisciplinary fields involving building science, fluid dynamics, computer science, and medical imaging disciplines. In the future, an integrated approach can lead to digital/in-silico representations of the human respiratory airway able to predict the inhaled particle exposure and its toxicology effect.

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Section: Indoor Inhalation Exposurementioning

confidence: 99%

Section: Indoor Inhalation Exposurementioning

confidence: 99%

From indoor exposure to inhaled particle deposition: A multiphase journey of inhaled particles

Inthavong

2019

Exp. Comput. Multiph. Flow

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“…One of the most important decisions that have to be made in any numerical study of fluid flow is the choice of the turbulence model as it bears a substantial effect on the accuracy of the result. A large number of studies in the literature have reported assessment of different turbulence models for single phase flow, particularly in the areas of aerodynamics (e.g., Menter, 1994;Bardina et al, 1997;Walsh and Leong, 2004;Cheng-Hu et al, 2005;Zhai et al, 2007;Baxevanou and Fidaros, 2008;El-Behery and Hamed, 2011;Sagol et al, 2012;Heschl et al,2013). However, few studies have been conducted to investigate the effectivity of various turbulence models in simulating two-phase pipeline flow.…”

Section: Introductionmentioning

confidence: 99%

CFD simulation of horizontal oil-water flow with matched density and medium viscosity ratio in different flow regimes

Shi

Gourma

Yeung

2017

Journal of Petroleum Science and Engineering

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Simulation of horizontal oil-water flow with matched density and medium viscosity ratio ( ⁄ =18.8) in several different flow regimes (core annular flow, oil plugs/bubbles in water and dispersed flow) was performed with the CFD package FLUENT in this study. The volume of fluid (VOF) multiphase flow modeling method in conjunction with the SST k-ω scheme was applied to simulate the oil-water flow. The influences of the turbulence schemes and wall contact angles on the simulation results were investigated for a core annular flow (CAF) case.The SST k-ω turbulence scheme with turbulence damping at the interface gives better predictions than the standard k-ε and RNG k-ε models for the case under consideration. The flow regime of density-matched oil-water flow with medium viscosity ratio, or more generally speaking, the flow regime of fluids where the surface tension is playing a prevailing role is sensitive to the wall contact angle. Simulation results were compared with experimental counterparts. Satisfactory agreement in the prediction of flow patterns were obtained for CAF and oil plugs/bubbles in water. The simulation results also demonstrated some detailed flow characteristics of CAF with relatively low-viscosity oil (oil viscosity one order higher than the water viscosity in the present study compared to the extensively studied CAF with oil viscosity being two to three orders higher than the water viscosity). Different from the velocity profiles of high-viscosity oil CAF where there is sharp change in the velocity gradient at the phase interface with velocity across the oil core being roughly flat, there is no sharp change in the velocity gradient at the phase interface for CAF with relatively low-viscosity oil.

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“…Heschl et al used various linear and non-linear RANS turbulence models k-ε, k-ω and v²-ƒ in several test cases such as linear free jet, plane wall jet, 2D room geometry and 3D room geometry with partition to improve the prediction of linear diffuser airflow patterns inside the room (Heschl et al, 2013). Generally, the results indicated that all turbulence models show good agreement with the experimental data and the proposed non-linear turbulence model can improve the prediction of the airflow patterns inside the room.…”

Section: Introductionmentioning

confidence: 99%

Study the Effect of Ceiling Air Diffuser Blade and Lip Angles Using CFD

Awwad¹,

Mohamed²,

Fatouh³

2017

AJTE

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The objective of the present work is to investigate the airflow characteristics inside a room through a 5-blade square louver face ceiling air diffuser using CFD to improve occupant's thermal comfort. Several blades angles (45°, 60° and 65°) and lip angles (0°, 5°, 10°, and 15°) were installed inside the room model. The realizable k-ε turbulence model was used to simulate all the 3D cases. In the paper, the results of 5blade louver face diffuser with 60° blade angle and horizontal lip are compared with 5-blade louver face diffuser with 45° and 65° blade angles with horizontal lip. Then, the effect of lip angle is investigated and compared with the results from a diffuser with a 60° and horizontal lip. The results showed that the diffuser with a 65° blade angle provides jet air velocity higher than 60° beside air patterns cling with room ceiling, which enhances the surface (Coanda) effect and provides lower temperature gradients than 60°. Therefore, it is suitable to install in larger spaces in order to reduce drafts on space occupants and reduce installation costs. On the other hand, the results indicated that the diffuser model with a 45° blade angle and 0° lip angle provides cone-shaped air patterns without any being attached to the room ceiling, therefore this type is preferable for installation in rooms with larger height or inside areas that require relatively low noise levels. Moreover, increasing the diffuser lip angle to 15° allows air patterns relatively to leave the room ceiling, and reach thermal comfort conditions without draft faster than the 0° lip angle.

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Evaluation and improvements of RANS turbulence models for linear diffuser flows

Cited by 34 publications

References 22 publications

From indoor exposure to inhaled particle deposition: A multiphase journey of inhaled particles

From indoor exposure to inhaled particle deposition: A multiphase journey of inhaled particles

CFD simulation of horizontal oil-water flow with matched density and medium viscosity ratio in different flow regimes

Study the Effect of Ceiling Air Diffuser Blade and Lip Angles Using CFD

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