Explicit numerical simulation of suspension flow with deposition in porous media: influence of local flow field variation on deposition processes predicted by trajectory methods

2003 ◽  
Vol 58 (7) ◽  
pp. 1271-1288 ◽  
Author(s):  
M.J Biggs ◽  
S.J Humby ◽  
A Buts ◽  
U Tüzün
Keyword(s):  
Numerical Simulation ◽  
Porous Media ◽  
Flow Field ◽  
Suspension Flow ◽  
Media Influence ◽  
Field Variation ◽  
Local Flow ◽  
Deposition Processes ◽  
Trajectory Methods

scholarly journals SPH Simulation of Interior and Exterior Flow Field Characteristics of Porous Media

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 918 ◽  
Author(s):  
Shijie Wu ◽  
Matteo Rubinato ◽  
Qinqin Gui
Keyword(s):  
Numerical Simulation ◽  
Porous Media ◽  
Flow Field ◽  
Boundary Conditions ◽  
Water Waves ◽  
Flow Behavior ◽  
Simulation Method ◽  
Interface Problem ◽  
Ocean Engineering ◽  
Flow Field Characteristics

At the present time, one of the most relevant challenges in marine and ocean engineering and practice is the development of a mathematical modeling that can accurately replicate the interaction of water waves with porous coastal structures. Over the last 60 years, multiple techniques and solutions have been identified, from linearized solutions based on wave theories and constant friction coefficients to very sophisticated Eulerian or Lagrangian solvers of the Navier-Stokes (NS) equations. In order to explore the flow field interior and exterior of the porous media under different working conditions, the Smooth Particle Hydrodynamics (SPH) numerical simulation method was used to simulate the flow distribution inside and outside a porous media applied to interact with the wave propagation. The flow behavior is described avoiding Euler’s description of the interface problem between the Euler mesh and the material selected. Considering the velocity boundary conditions and the cyclical circulation boundary conditions at the junction of the porous media and the water flow, the SPH numerical simulation is used to analyze the flow field characteristics, as well as the longitudinal and vertical velocity distribution of the back vortex flow field and the law of eddy current motion. This study provides innovative insights on the mathematical modelling of the interaction between porous structures and flow propagation. Furthermore, there is a good agreement (within 10%) between the numerical results and the experimental ones collected for scenarios with porosity of 0.349 and 0.475, demonstrating that SPH can simulate the flow patterns of the porous media, the flow through the inner and outer areas of the porous media, and the flow field of the back vortex region. Results obtained and the new mathematical approach used can help to effectively simulate with high-precision the changes along the water depth, for a better design of marine and ocean engineering solutions adopted to protect coastal areas.

Diffusion limited mixing in heterogeneous porous media

2021 ◽  
Author(s):  
Mayumi Hamada ◽  
Pietro de Anna
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Flow Field ◽  
Fast Diffusion ◽  
Pore Scale ◽  
Mixing Processes ◽  
Local Flow ◽  
Gaussian Shape ◽  
Diffusion Limited ◽  
The Impact

<p><span><span>A pore-scale description of the transport and mixing processes is particularly relevant when looking at biological and chemical reactions. For instance, a microbial population growth is controlled by local concentrations of nutrients and oxygen, and chemical reaction are driven by molecular-scale concentration gradients. The heterogeneous flow field typically found in porous media results from the contrast of velocities that deforms and elongates the mixing fronts between solutes that often evolves through a lamella-like topology. For continuous Darcy type flow field a novel framework that describes the statistical distribution of concentration being transported was recently developed (Le Borgne et al., JFM 2015). In this model, concentrations in each lamella are distributed as a Gaussian-like profile which experiences diffusion in the transverse direction while the lamella is elongated by advection along the local flow direction. The evolving concentration field is described as the superposition of each lamella. We hypothesize that this novel view, while perfectly predicting the distribution of concentration for Darcy scale mixing processes, will breakdown when the processes description is at the pore scale. Indeed the presence of solid and impermeable boundaries prevents lamella concentration to diffuse freely according to the a Gaussian shape, and therefore changes the mixing front profile, the lamella superposition and elongation rules. P</span></span><span><span>revious work (Hamada et al, PRF, 2020) demonstrated that </span></span><span><span>the presence of solid boundaries leads to an enhanced diffusion and thus fast homogenization of concentrations. </span></span><span><span>In a purely diffusive process the local mixing time is reduced by a factor of ten with respect to the </span></span><span><span>continuous case and concentration gradient are dissipated exponentially fast while a </span></span><span><span>power law decrease </span></span><span><span>is </span></span><span><span>observed in continuous medium.</span></span><span><span> To investigate the impact of these mechanisms on mixing we developed a</span></span><span><span>n experimental set-up to visualize and quantify the displacement of a conservative tracer in a synthetic porous medium. The designed apparatus allows to obtain high resolution concentration measurement</span></span><span><span>s</span></span><span><span> at the pore scale. We show that the resulting mixing measures, computed in terms of concentration probability density function and dilution index values, diverge </span></span><span><span>qualitatively and quantitatively from what happens in a continuous domain. These observations suggest </span></span><span><span>that description of pore-scale diffusion-limited mixing requires model that takes into account the confined nature of porous medium, </span></span><span><span>otherwise we will tend to overestimate concentration value and neglect the fast diffusion dynamic taking place at microscopic level.</span></span></p>

Numerical simulation of the flow field in a bioreactor

2000 ◽  
Vol 41 (4-5) ◽  
pp. 207-210 ◽  
Author(s):  
S. Ester ◽  
X. Guo ◽  
A. Delgado
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Numerical Method ◽  
Mechanical Behaviour ◽  
Numerical Code ◽  
Measurement Instruments ◽  
Local Flow ◽  
Velocity Pressure ◽  
Detailed Picture ◽  
Good Agreement

In order to give detailed information about the local flow field in a bioreactor a numerical method has been developed. This method gives information about the velocity, pressure and temperature in each point of the reactor, avoiding the problems caused by placing measurement instruments inside. Comparisons of experiments and numerical results show good agreement. The functionality and physical fundamentals of this tool are described. This is followed by explaining a reasonable application of the numerical code in the field of biological reactors. The reactors considered are filled with polydisperse, spherical support particles. From the results of the simulation a detailed picture of a reactor's fluid mechanical behaviour is drawn. This includes the quantification of mechanical stresses on the biofilm surface as well as information about the inflow, outflow and channelling behaviour of a reactor. Furthermore the effect of polydisperse support carries in discussed.

scholarly journals Influence of Grain Size Transition on Flow and Solute Transport through 3D Layered Porous Media

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 5) ◽  
Author(s):  
Zhi Dou ◽  
Xueyi Zhang ◽  
Jinguo Wang ◽  
Zhou Chen ◽  
Yunbo Wei ◽  
...  
Keyword(s):  
Grain Size ◽  
Porous Medium ◽  
Porous Media ◽  
Flow Field ◽  
Solute Transport ◽  
Transition Zone ◽  
Significant Influence ◽  
Local Flow ◽  
Layered Porous Media ◽  
Distribution Of Flow

Abstract Soils and other geologic porous media often have contrasting grain size layers associated with a grain size transition zone between layers. However, this transition zone is generally simplified to a plane of zero thickness for modeling assumption, and its influence has always been neglected in previous studies. In this study, an approach combining a deposition process and a random packing process was developed to generate 3D porous media without and with consideration of the transition zone. The direct numerical models for solving the flow and concentration fields were implemented to investigate the influence of the grain size transition on flow and solute transport. Our results showed that although the transition zone occupied 13.6% of the entire layered porous medium, it had little influence on the distribution of flow velocity at the scale of the entire layered porous medium. However, the transition zone had a significant influence on the local flow field, which was associated with the increased spatial variability of velocity and the varied distribution of flow velocity. This varied local flow field could increase the solute residence time and delay the breakthrough time for solute transport. Although using both the advection-dispersion equation (ADE) and the mobile and immobile (MIM) models to fit the breakthrough curves (BTCs) for solute transport through layered porous media resulted in trivial errors, the ADE model failed to capture the influence induced by the local flow field, especially the influence of the transition zone. In contrast, the MIM model was shown to be able to capture the influence of the transition on solute transport. It was found that the mass transfer rate α, a parameter of the MIM model, was significantly improved by the presence of the transition zone, while it decreased as the transition zone fraction increased. Our study emphasized that the transition zone can vary the local flow field at the pore scale, while it has little influence on the hydraulic properties (e.g., hydraulic conductivity) of the macroscale flow field. However, the local flow field varied by the transition zone has a significant influence on solute transport.

Numerical Simulation and Performance Prediction of Multistage Canned Motor Pump

2016 ◽  
Author(s):  
Bin Xia ◽  
Fan-Yu Kong ◽  
Yuxing Bai ◽  
Xiaohui Duan
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Performance Prediction ◽  
Three Dimensional ◽  
Internal Flow ◽  
Main Flow ◽  
Three Dimensional Model ◽  
Local Flow ◽  
And Performance ◽  
Canned Motor

Due to the advantages of high head and no leakage, multistage canned motor pump is widely used in oil industry, chemical industry, national defense and atomic energy. In order to meet the needs of the market, the multistage canned motor pump is designed. This paper introduced the hydraulic design and structural design. In order to optimizing the performance of the pump, this paper designed and used multistage canned motor pump DBP15–50×8 as the research object. Three-dimensional model of the main flow passage components is built and the mesh is generated respectively by using Pro/E and ICEM software, and we calculated the whole internal flow field of the pump that was selected by using ANSYS CFX14.0 software, achieving the pressure and velocity distribution in the pump and the internal details of flow in impeller and other main flow components. The post-processing showed the fluid in sliding bearing section rotates around the shaft, so the local flow is disorder. The comparison of the performance prediction and the experiment shows that the error is low. The cavitating turbulent flow in the flow field was numerically simulated by using the cavitation model. The cavitation phenomena didn’t occur in the experiments. The condition meets the result of numerical simulation.

Research on the Numerical Simulation of Internal Flow Field and Energy Efficiency of Ventilator

2015 ◽  
Vol 713-715 ◽  
pp. 602-605
Author(s):  
Zhu Jue Tong ◽  
Xiao Ling Wang ◽  
Kai Zhang ◽  
Shu Xing Wu
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Energy Efficiency ◽  
Flow Field ◽  
Three Dimensional ◽  
Internal Flow ◽  
Secondary Flows ◽  
Local Flow ◽  
Gap Flow ◽  
Computational Fluid Dynamics Cfd

In the present study, the effects of ventilator geometries on the its performance were numerically simulated using the computational fluid dynamics (CFD) program. For a certain type ventilator, three-dimensional inner flow field was derived firstly, such as local flow field at the meridional and rotary plane of ventilator, the gap flow between the impeller and air outlet, and the secondary flows in impeller channel were studied in detail, and some suggestions are given to improve the profile of velocity. The above results would be helpful to the optimization and modification of ventilator.

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