scholarly journals A generalized model for pumping well hydraulics in confined aquifers

2018 ◽  
Vol 20 (5) ◽  
pp. 1085-1099
Author(s):  
Shadab Anwar
Keyword(s):  
Discharge Rate ◽  
Circular Disk ◽  
Velocity Model ◽  
Well Test ◽  
Generalized Model ◽  
Heterogeneous Aquifer ◽  
Well Hydraulics ◽  
Confined Aquifers ◽  
Boltzmann Method ◽  
Infinite Linear

Abstract A generalized model for well hydraulics in confined aquifers is presented. The lattice Boltzmann method (LBM)-based altered-velocity model is used to simulate well hydraulics in homogeneous and heterogeneous confined aquifers for different pumping conditions. LBM is applied to simulate well hydraulics in two different configurations of heterogeneous aquifer, where (1) a circular disk of material or (2) an infinite linear strip of material is embedded in a matrix of differing hydraulic properties. The effect of hydrogeologic boundaries on drawdown curve in confined aquifers is simulated using LBM. The LBM is further applied to simulate drawdown during harmonic pumping well test. The LBM data in lattice units are scaled to physical units using non-dimensional discharge rate and diffusion length. The results from LBM were found to be sensitive to the relaxation parameter and the RMS error for drawdown was found to be less than 1% for later time. This work will verify the potential of LBM to simulate well hydraulics in homogeneous and heterogeneous confined aquifers for constant, step, and harmonic pumping.

scholarly journals Numerical simulation model of vertical velocity distribution in a channel with artificial floating bed

2020 ◽  
Vol 20 (5) ◽  
pp. 1922-1932
Author(s):  
Yu Bai ◽  
Yonggang Duan ◽  
Wenjun Yue
Keyword(s):  
Turbulent Flows ◽  
Vertical Velocity ◽  
Velocity Model ◽  
Mean Value ◽  
Coefficient Of Determination ◽  
Eddy Simulation ◽  
Proposed Model ◽  
Large Eddy ◽  
The Mean ◽  
Boltzmann Method

Abstract Artificial floating bed (AFB), as a novel type of ecological drainage ditch, is extensively used worldwide. To more effectively design the structure of the project, an accurate velocity model is required. In this study, a two-dimensional Lattice Boltzmann method (LBM) was employed for the simulation of the vertical velocity in a channel with AFB. The large eddy simulation (LES) was conducted to simulate turbulent flows, while the drag force of AFB was discretized with a centered scheme. Two sets of experimental data were used to verify the model, the mean value of root mean square error (RMSE) and coefficient of determination (R2) are 0.93 and 1.84, respectively. This proved that the proposed model is more effective to simulate the vertical velocity in a channel with AFB.

Numerical Simulations of Flows in Cerebral Aneurysms Using the Lattice Boltzmann Method

2020 ◽  
Author(s):  
Susumu Osaki ◽  
Kosuke Hayashi ◽  
Hidehito Kimura ◽  
Eiji Kohmura ◽  
Akio Tomiyama
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Flow Characteristics ◽  
Cerebral Aneurysms ◽  
Collision Operator ◽  
Velocity Model ◽  
Outflow Boundary Condition ◽  
Aneurysm Wall ◽  
Outflow Boundary ◽  
Boltzmann Method

Abstract The lattice Boltzmann method (LBM) is used to simulate blood flows in cerebral aneurysms and the effects of the outflow boundary condition on predictions are studied. The LBM utilizes the D3Q19 discrete velocity model, the multiple-relaxation time collision operator (MRT), and the interpolated bounce-back rule to treat complex aneurysm shapes. Flow characteristics in regions of a large fluctuation in the wall shear stress (WSS) were then investigated using the LBM to understand the relation between the flow structure and the aneurysm wall remodeling. As a result the following conclusions were obtained under the present range of the numerical condition: (1) even with significant changes in the flow rate distributions at outflow boundaries, the WSS in an aneurysm is not much affected if the boundaries are far from the aneurysm, and (2) the geometry of an aneurysm and the main artery largely affects the formation of large WSS fluctuation regions, which may thickens the aneurysm wall due to inflammation-induced wall remodeling.

Canola paste extrusion for feeding supercritical extractors

1995 ◽  
Vol 73 (5-6) ◽  
pp. 304-309 ◽  
Author(s):  
Fangzhi Wang ◽  
Axel Meisen
Keyword(s):  
Discharge Rate ◽  
Velocity Model ◽  
Pressure Transducers ◽  
Single Screw Extruder ◽  
Discharge Rates ◽  
Hydraulic Motors ◽  
Paste Extrusion ◽  
Component Velocity ◽  
Extraction Processes ◽  
Practical Implications

A custom-built, single-screw extruder (barrelf 0.44 m long, 36.75 mm ID; screw flight angles: 5.98°, 7.97°; or 9.94°; average screw flight: 4.9 mm high, 3 mm wide; flight-top to barrel clearance: 0.0254 mm) was developed for continuously feeding precrushed Canola seed pastes into supercritical fluid extractors. The screw was driven by two variable-speed hydraulic motors and rotated typically at 66.5, 88.5, or 100.5 rpm. The pressures and temperatures along the extruder barrel were measured with six iron–Constantan thermocouples and four pressure transducers, respectively. The discharge rate of the paste was determined gravimetrically and was found to vary from approximately 1.7 to 9.5 kg h−1 for average discharge pressures ranging from 30 to 10 MPa. The average pressure along the barrel was found to increase almost linearly. A three-component velocity model was developed to simulate the extruder performance and verified by comparison with experimental data obtained by using a Newtonian fluid having a viscosity of 130 Pa s. The model over predicted the discharge rates of Canola pastes unless allowance is made for slip. The practical implications for supercritical extraction processes are discussed.

scholarly journals Pore pressure prediction using seismic velocity modeling: case study, Sefid-Zakhor gas field in Southern Iran

2019 ◽  
Vol 10 (3) ◽  
pp. 1051-1062 ◽  
Author(s):  
Zahra Bahmaei ◽  
Erfan Hosseini
Keyword(s):  
Pore Pressure ◽  
Seismic Velocity ◽  
Velocity Model ◽  
Wellbore Stability ◽  
Well Test ◽  
Drilling Mud ◽  
Gas Field ◽  
Seismic Section ◽  
Interval Velocity ◽  
Seal Integrity

AbstractPore pressure estimation is important for both exploration and drilling projects. During the exploration phase, a prediction of pore pressure can be used to evaluate exploration risk factors including the migration of formation fluids and seal integrity. To optimize drilling decisions and well planning in abnormal pressured areas, it is essential to carry out pore pressure predictions before drilling. Mud weight and fracture gradient are essential parameters to have wellbore stability, prevent blowout, lost circulation, kick, sand production and reservoir damages. Predrill pore pressure accurate prediction allows the appropriate mud weight to be selected and allows the casing program to be optimized, thus enabling safety by preventing wellbore collapse and economic drilling by reducing the cost. The goal of this study is to estimate pore pressure relation with subsurface velocity in the Sefid-Zakhor gas field. Manufactured sonic logs are modified using the check shot interval velocity of Sefid-Zakhor well No. 1. The final acoustic impedance model is converted to the velocity model by removing density. Finally, the velocity model is converted to pore pressure using Bowers (in: IADC/SPE drilling conference proceedings, 1995) relation. The results of the pore pressure model are validated by pore pressure data obtained by the MDT well test tool. Generally, the results show the normal trend for pore pressure in the area, except in the left side of the anticline in the 2D seismic section, because of tectonic uplifting.

Lattice Boltzmann Method for Numerical Simulation of Circular Tube Forced Convection

2013 ◽  
Vol 765-767 ◽  
pp. 460-464
Author(s):  
Shou Guang Yao ◽  
Gong Li Wang ◽  
Qing Fang Cheng ◽  
Chang Jiang Zhou
Keyword(s):  
Lattice Boltzmann Method ◽  
Forced Convection ◽  
Lattice Boltzmann ◽  
Circular Tube ◽  
Velocity Model ◽  
Lattice Boltzmann Model ◽  
Distribution Model ◽  
Boltzmann Method ◽  
Thermal Lattice Boltzmann ◽  
Boltzmann Model

This paper established the thermal Lattice Boltzmann model of fluid flow and heat transfer, which is based on double lattice Boltzmann distribution model [. The temperature distribution adopted the higher accuracy velocity model. Based on this thermal lattice Boltzmann model, this paper simulated forced convection of circular tube fluid. Comparing the simulation results with the traditional CFD calculation results, we could find that the thermal lattice Boltzmann method have unique advantages in effectiveness and flexibility than the traditional calculation method.

scholarly journals 3D Simulation of Self-Compacting Concrete Flow Based on MRT-LBM

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Liu-Chao Qiu ◽  
Yu Han
Keyword(s):  
Lattice Boltzmann ◽  
Three Dimensional ◽  
Velocity Model ◽  
Self Compacting Concrete ◽  
Numerical Examples ◽  
Multiple Relaxation Time ◽  
Constitutive Mode ◽  
Boltzmann Method ◽  
Discrete Velocity Model ◽  
Concrete Flow

A three-dimensional multiple-relaxation-time lattice Boltzmann method (MRT-LBM) with a D3Q27 discrete velocity model is applied for simulation of self-compacting concrete (SCC) flows. In the present study, the SCC is assumed as a non-Newtonian fluid, and a modified Herschel–Bulkley model is used as constitutive mode. The mass tracking algorithm was used for modeling the liquid-gas interface. Two numerical examples of the slump test and enhanced L-box test were performed, and the calculated results are compared with available experiments in literatures. The numerical results demonstrate the capability of the proposed MRT-LBM in modeling of self-compacting concrete flows.

scholarly journals Flowing wells: history and role as a root of groundwater hydrology

2020 ◽  
Author(s):  
Xiao-Wei Jiang ◽  
John Cherry ◽  
Li Wan
Keyword(s):  
19Th Century ◽  
Groundwater Hydrology ◽  
New Paradigm ◽  
Early 19Th Century ◽  
Unconfined Aquifers ◽  
Well Hydraulics ◽  
Confined Aquifers ◽  
The 1960S ◽  
Flowing Well

Abstract. The spewing of groundwater in flowing wells is a phenomenon of interest to the public, but little attention has been paid to the role of flowing wells on the science of groundwater. This study reviews that answering to problems related to flowing wells since the early 19th century led to the birth of many fundamental concepts and principles of groundwater hydrology. The concepts stemmed from flowing wells in confined aquifers include permeability and compressibility, while the principles include Darcy's law, role of aquitards on flowing well conditions and the piston flow pattern, steady-state well hydraulics in confined aquifers, and transient well hydraulics towards constant-head wells in confined or leaky aquifers, all of which are applicable even if flowing well conditions have disappeared. Due to the widespread occurrence of aquitards, there is a long-lasting misconception that flowing wells must be geologically-controlled. The occurrence of flowing wells in topographic lows of unconfined aquifers was anticipated in 1940 and later verified in the 1960s, accompanying with the birth of the theory of topographically-driven groundwater flow, which has been considered as a paradigm shift in groundwater hydrology. Based on studies following this new paradigm, several preconditions of flowing wells given in the 19th century have been found to be not necessary at all. This historical perspective of the causes of flowing well conditions and the role of flowing wells on the science of groundwater could lead to a deeper understanding of the evolution of groundwater hydrology.

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