The evolutionary process of mixing induced by Rayleigh–Taylor (RT) and Richtmyer–Meshkov (RM) instabilities typically progresses through three stages: initial instability growth, subsequent transition ultimate turbulent mixing. Accurate prediction this entire is crucial for both scientific research engineering applications. For applications, Reynolds-averaged Navier–Stokes (RANS) simulation stands as the most viable method currently. However, it noteworthy that existing RANS models are...

This article focuses on a subgrid-scale (SGS) eddy viscosity model based helicity which is derived from our previous research [Yu et al., “Subgrid-scale for helical turbulence,” Phys. Fluids 25, 095101 (2013)] large-eddy simulation of transition and turbulence in compressible flows. Based the character boundary layer over flat plate, we obtain theoretical analysis that this can automatically distinguish laminar flow also simulate well. Meanwhile, an priori test using direct numerical (DNS)...

Abstract Direct numerical simulation (DNS) of transition over a hypersonic lifting body model HyTRV developed by China Aerodynamics Research and Development Center is performed. The free-stream parameters are: the Mach number 6, unit Reynolds 10000/mm, temperature 79 K, angle attack 0, wall 300 K. Weak random blowing-and-suction perturbations in leading range are used to trigger transition. A high order finite-difference code OpenCFD authors for simulation, grid convergence test shows that...

Similar to the kinetic energy cascade, a helicity cascade is also basic and key process in generation evolution of turbulent flows. Furthermore, flux (HF) plays crucial role between two scales cascade. In this study, we will supply new helical model constrained by for large eddy simulation compressible Then, order obtain more precise HF, local coefficient modeled HF determined artificial neural network (ANN) method. The combines merits high robustness correlation with real turbulence. test...

A new one-equation eddy-viscosity model based on subgrid-scale (SGS) helicity is introduced in this paper for large-eddy simulation (LES) of turbulent flows. First, the governing equation SGS deduced from incompressible Navier–Stokes equations, and it reflects transfer small-scale that has been filtered out. We deduce a certain functional relation between eddy viscosity kinetic energy spectra homogeneous isotropic helical turbulence. For improving accuracy, each unclosed term modeled...

Kinetic energy flux (KEF) is an important physical quantity that characterizes cascades of kinetic in turbulent flows. In large-eddy simulation (LES), it crucial for the subgrid-scale (SGS) model to accurately predict KEF turbulence. this paper, we propose a new eddy-viscosity SGS constrained by properly modelled LES compressible wall-bounded The methodology has advantages both accurate prediction and strong numerical stability LES. We can obtain approximate tensor-diffusivity model, which...

A quasi-dynamic subgrid-scale (SGS) kinetic energy one-equation eddy-viscosity model is introduced in this paper for large-eddy simulation (LES) of compressible flows. With the additional SGS equation, can be predicted properly. Then, using dual constraints and flux, determined exactly. Taking a similar scheme as expansion stress, other unclosed quantities equations to solved could well modelled separately. Therefore, with advance equations, all coefficients dynamically. Differing from...

The wall-adapting local eddy-viscosity (WALE) model in large-eddy simulation can well predict wall-bounded flows but it is also known for excessive dissipation. In this study, we apply the minimum-dissipation to constrain WALE compressible and obtain coefficient of model. Through process, dissipation be lower while still maintains strong stability. modified model, isotropic part subgrid-scale (SGS) stress reconstructed. filtered total energy equation, all extra SGS unclosed terms (besides...

In this paper, large-eddy simulation of the interaction between a shock wave and hypersonic turbulent boundary layer in compression corner with fixed 34° deflection angle at Ma = 6 for different Reynolds number cases is conducted. For investigating effects cases, three where free-stream numbers are 14000, 20000, 30000/mm selected. The averaged statistics, such as mean velocity, skin friction, heat flux, wall pressure, used paper. flow structures ramp including region discussed. decomposition...

Radiant floor heating as a new type of energy-saving method has more and used in modern building project. According to the different heat source, radiant is divided into low temperature hot-water electrical heating. This paper analyzes transfer process structure layer system, establishes two dimensional steady mathematic model, numerical calculation using Fluent software. Respectively simulated when materials different, The analysis results show that: for heating, material soft wood, ground...

The oil pipeline burying divulging pollutant was taken as the object of study in this paper, heat transfer and mass process which soil porous medium were carried by numerical analysis. phase change for multiphase flow leakage buried pipelines oil, gas water low temperature considered, impact on high viscosity properties analyzed. It cited leak using Fluent at different times during course earth field , / distribution surface temperature, results showed that : there existed a big difference...

Considered influence of buried pipeline leakage crude oil pollutants multiphase flow migration phenomenon effects, numerical model was established to road leak process simplified for two-dimension problem, simulation used with the CFD software FLUENT on caused pollution calculation carried out in two species workers condition one phase and around earth temperature field, speed field distributions oil/water soil porous media. Analysis comparison results indicated that: 1) affected region...

The subgrid-scale (SGS) kinetic energy has been used to predict the SGS stress in compressible flow and it was resolved through transport equation past studies. In this paper, a new eddy-viscosity model is proposed using artificial neural network obtain precisely, instead of equation. Using infinite series expansion reserving first term expanded term, we an approximated energy, which high correlation with real energy. Then, coefficient modelled by more accurate method compared obtained from...

Oily wastewater from oil field by microwave induced and catalytic demulsification was studied in this paper. The advantages prospects of the technology analyzed. Microwave treatment oilfield has such as equipment occupies a small space, easy to operate, portable, transport, installation commissioning, short reaction time, high efficiency, discharge water which good quality, temperature other factors do not affect effect so on. also bactericidal applicable treat both South North China. When...

The mixing induced by the Rayleigh–Taylor (RT) instability occurs widely in various natural phenomena and engineering applications, such as inertial confinement fusion. transition RT process is key affecting evolution. At present, research mainly involves criteria based on global quantities, statistical analysis of mixedness parameters kinetic energy, so on. A few studies have paid attention to evolution vorticity its intensity, enstrophy, during process. However, previous inferred that...

Turbulent mixing is a pivotal phenomenon in fusion research with profound implications for energy gain. A Reynolds-averaged Navier–Stokes model capable of predicting realistic transition processes significant importance applications, yet such remains elusive. This work addresses the limitations prevalent global criteria, proposing new idea to quantify local characteristics based on state, recognizing its direct relevance reaction rates. We delve into description and analysis spatiotemporal...

This paper established mathematic and physic model of buried oil pipelines leaking in porous media soil. Make use FLUENT software to simulate crude phase change non-phase the soil cold regions. The result shows that: temperature over leakage hole diffusion process is higher than not considering change. diffuse earth’s surface needs more time. And speed diffusing underground basically same. earth temperature’s variation without lags behind

Our country building energy consumption is amazing, ventilation about more than 20% of the whole , its saving potential very great, How to reduce and still keep good indoor air quality, makes natural ways becoming focus attention. This paper studies solar chimney，one strengthening ventilation，strengthening ventilation；At same time use FLUENT software simulate chimney model，Analysis calculated results, get a reasonable thickness flow meet ventilated requirements, so as provide theoretical...