The Design of a Three-Dimensional Physical Modeling System for Real-Time Groundwater Flows

In the past decades,physical modeling has been widely used in hydrogeology for teaching,studying and exhibition purposes.Most of these models are used to illustrate hydrogeological profiles,but few can depict three-dimensional groundwater flows,making it impossible to validate groundwater flows simulated by numerical methods with physical modeling.

Modeling and simulation of non-isothermal three-phase flow for accurate prediction in underbalanced drilling

The present study aims at investigating the effect of temperature variation due to heat transfer between the formation and drilling fluids considering influx from the reservoir in the underbalanced drilling condition. Gas-liquid-solid three-phase flow model considering transient thermal interaction with the formation was applied to simulate wellbore fluid to calculate the wellbore temperature and pressure and analyze the influence of different parameters on fluid pressure and temperature distribution in annulus. The results show that the non-isothermal three-phase flow model with thermal consideration gives more accurate prediction of bottom-hole pressure(BHP) compared to other models considering geothermal temperature. Viscous dissipation, the heat produced by friction between the rotating drilling-string and well wall and drill bit drilling, and influx of oil and gas from reservoir have significant impact on the distribution of fluid temperature in the wellbore, which in turn affects the BHP. Bottom-hole fluid temperature decreases with increasing liquid flow rate, circulation time, and specific heat of liquid and gas but it increases with increasing in gas flow rate. It was found that BHP is strongly depended on the gas and liquid flow rates but it has weak dependence on the circulation time and specific heat of liquid and gas. BHP increase with increasing liquid flow rate and decreases with increasing gas flow rate.

NUMERICAL INVESTIGATION OF THREE-DIMENSIONAL VISCOUS INCOMPRESSIBLE FLOWS IN DIVERGENT CURVED CHANNELS AND TURBULENT MODEL STUDY

In order to make the numerical calculation of viscous flows more convenient for the flows in channel with complicated profile governing equations expressed in the arbitrary curvilinear coordinates were derived by means of Favre density-weighted averaged method, and a turbulent model with effect of curvature modification was also derived. The numerical calculation of laminar and turbulent flown in divergent curved channels was carried out by means of parabolizeil computation method. The calculating results were used to analyze and investigate the aerodynamic performance of talor cascades in compressors preliminarily.

Three-Dimensional Tidal Model and Its Application to Numerical Simulation of Water Quality in Coastal Waters

The turbulence mechanism plays an important part in the mixing process and momentum transfer of turbulence. A three-dimensional Prandtl mixing length tidal model has been developed to simulate tidal flows and water quality. The eddy viscosities and diffusivities are computed from the Prandtl mixing length model. In order to model the water quality of an estuary or coastal area many interdependent processes need to be simulated. These may be conveniently separated into three main groups: transport and mixing processes, biochemical interaction of water quality variables and the utilization and re-cycling of nutrients by living matter. The model simulates full oxygen and nutrient balance, primary productivity and the transport, reaction mechanism and fate of pollutants over tidal time-scales. The model is applied to numerical simulation of tidal flows and water quality in Dalian Bay. The model has been calibrated against a limited data set of historical water quality observations and in general demonstrates excellent agreement with all available data.

Automatic measurement of three-phase contact angles in pore throats based on digital images

With the help of digital image processing technology, an automatic measurement method for the three-phase contact angles in the pore throats of the microfluidic model was established using the microfluidic water flooding experiment videos as the data source. The results of the new method were verified through comparing with the manual measurement data.On this basis, the dynamic changes of the three-phase contact angles under flow conditions were clarified by the contact angles probability density curve and mean value change curve. The results show that, for water-wetting rocks, the mean value of the contact angles is acute angle during the early stage of the water flooding process, and it increases with the displacement time and becomes obtuse angle in the middle-late stage of displacement as the dominant force of oil phase gradually changes from viscous force to capillary force. The droplet flow in the remaining oil occurs in the central part of the pore throats, without three-phase contact angle. The contact angles for the porous flow and the columnar flow change slightly during the displacement and present as obtuse angles in view of mean values, which makes the remaining oil poorly movable and thus hard to be recovered. The mean value of the contact angle for the cluster flow tends to increase in the flooding process, which makes the remaining oil more difficult to be recovered. The contact angles for the membrane flow are mainly obtuse angles and reach the highest mean value in the late stage of displacement, which makes the remaining oil most difficult to be recovered. After displacement, the remaining oils under different flow regimes are just subjected to capillary force, with obtuse contact angles, and the wettability of the pore throat walls in the microfluidic model tends to be oil-wet under the action of crude oil.

Analysis of the flow pattern and periodicity of gas–liquid–liquid three-phase flow in a countercurrent mixer-settler

In contrast to the concurrent mixer-settler,the interaction between the mixing and settling chambers have to be taken into account in the simulation of the countercurrent mixer-settler,and no work has been reported for this equipment.In this work,a three-phase flow model based on the Eulerian multiphase model,coupled with a sliding mesh model is proposed for a countercurrent mixer-settler.Based on this,the dispersed phase distribution,flow pattern,and pressure distribution are investigated,which can help to fill the gap in the operation mechanism.In addition,the velocity vector distribution at the phase port shows an intriguing phenomenon that two types of vectors with opposite directions are distributed on the left and right sides of the same plane,which indicates that the material exchange in the mixing and settling chambers is simultaneous.Analysis of this variation at this location by a fast Fourier transform(FFT)method reveals that it is mainly influenced by the mixing chamber and is consistent with the main period of the outlet flow fluctuations.Therefore,by monitoring the fluctuation of the outlet flow and then analyzing it by the FFT method,the state of the whole tank can be determined,which makes it promising for the design of control systems for countercurrent mixer-settlers.

A NEW UNSTEADY THREE DIMENSIONAL MODEL FOR MACROMOLECULAR TRANSPORT AND WATER FILTRATION ACROSS THE ARTERIAL WALL

A new unsteady three-dimensional convective-diffusive mathematical model for the transportation of macromolecules and water across the arterial wall was proposed . After the formation of leaky junctions due to the mitosis of endothelial cell of the arterial wall, the macromolecular transport happens surrounding the leaky cells. The arterial wall was divided into four layers: the endothelial layer, the subendothelial intima, the internal elastic lamina and the media for the convenience of research. The time-dependent concentration growth,the effect of the shape of endothelial cell and the effect of physiological parameters were analyzed. The analytical solution of velocity field and pressure field of water flow across the arterial wall were obtained; and concentration distribution of three macromolecules ; LDL,HRP and Albumin, were calculated with numerical simulation method. The new theory predicts, the maximum and distribution areas of time dependent concentration with round shape endothelial cell are both larger than that with ellipse-shape endothelial cell. The model also predicts the concentration growth is much alike that of a two-dimensional model and it shows that the concentration reaches its peak at the leaky junction where atherosclerotic formation frequently occurs and falls down rapidly in a limited area beginning from its earlier time growth to the state when macromolecular transfer approaches steadily. These predictions of the new model are in agreement with the experimental observation for the growth and concentration distribution of LDL and Albumin.

Study on short－range numerical forecasting of ocean current in the East China Sea—II．Three－dimensional diagnostic model and its application in the Bohai Sea

In this paper,a tbree-dimensional (3-D) baroclinic diagnostic model for short-range numerical forecast is proposed to calculate the monthly averaged flow field in the Bohai Sea. By using the model and monthly averaged tempeature and salinity date, monthly barotropic and baroclinic flow field are calculated,and 2-D and 3-D characteristics of flow are described and demonstrated. On the basis of the analysis of the modelling results and the observed temperature,salinity and wind data,the monthly and seasonal characteristics and generation mechanism of circulation in the Bohai Sea are also discussed. It is pointed out in this paper that in spring and autumn,the monthly averaged flow fields are not representative, for the wind direction varies in a wide range and the averaged wind field is much weaker than the instantaneous one. These results show the reliability of the model for describing the monthly characteristics in numerical forecast of ocean current.

Hall Effects on Unsteady MHD Three Dimensional Flow through a Porous Medium in a Rotating Parallel Plate Channel with Effect of Inclined Magnetic Field

In this paper, we make an initial value investigation of the unsteady flow of incompressible viscous fluid between two rigid non-conducting rotating parallel plates bounded by a porous medium under the influence of a uniform magnetic field of strength H0 inclined at an angle of inclination α with normal to the boundaries taking hall current into account. The perturbations are created by a constant pressure gradient along the plates in addition to the non-torsional oscillations of the upper plate while the lower plate is at rest. The flow in the porous medium is governed by the Brinkman’s equations. The exact solution of the velocity in the porous medium consists of steady state and transient state. The time required for the transient state to decay is evaluated in detail and the ultimate quasi-steady state solution has been derived analytically. Its behaviour is computationally discussed with reference to the various governing parameters. The shear stresses on the boundaries are also obtained analytically and their behaviour is computationally discussed.

A three-dimensional k-ε-k_p model in curvilinear coordinates for sediment movement and bed evolution

To aim at the substitution of the magnitude and direction of water flow movement near bed for those of bed load transport in solid-liquid two-phase one-fluid model, and to simulate the effect of secondary flow on transverse bed load transport in channel bends and the effect of bed slope on bed load trans- port in a better way, a three-dimensional k-ε-kp solid-liquid two-phase two-fluid model in curvilinear coordinates is solved numerically with a finite-volume method on an adaptive grid for studying wa- ter-sediment movements and bed evolution in a 120° channel bend. Numerical results show that the trajectories of solid-phase deviate from those of liquid-phase in the channel bend, and the deviation increases with the increase of the particle diameters. The calculated bed deformation by the k-ε-kp model is in better agreement with measured bed deformation than those by one-fluid model. It is proved that the k-ε-kp model can simulate the effect of secondary flow on lateral bed load transport with the higher accuracy than the one-fluid model.

Analysis of flow of visco-elastic nanofluid with third order slips flow condition,CattaneoChristov heat and mass diffusion model

This communication reports,the flow of viscoelastic nanofluid with third order slip flow condition,Cattaneo-Christov heat and mass diffusion model.The joined non-linear ordinary differential equations(ODEs)were acquired from the partial differential equations,which are resulting from conservation of momentum,energy and species.By means of similarity transformations these ODEs were alerted into dimensionless form and solved numerically by means of bvp4c solver.The effects of different parameters on velocity,temperature,and concentration profiles were examined and discussed in depth by means of graphs and tables.The outcomes indicate that the velocity profile along both x and y directions augment with higher values of viscoelastic parameter.The results also confirm that an increment in the values of ratio parameter tends to grow up the velocity profile alongside y-direction.However,the velocity profile along x-direction slows down with increment in the value of third order slip parameter.Also,the results illustrate that diminution in temperature is observed for higher Sc in the region of boundary layer.Besides,both temperature and concentration can be improved via higher Biot number.The upshots also portrayed that the local skin friction coefficient augmented within mounting values of viscoelastic fluid parameter.Furthermore,for finer values of Biot number both local Nusselt number and the local Sherwood number are enlarged.In addition,the most favorable agreement is observed among the results of the present study and those of the earlier studies.

FLOW STRUCTURE AND SEDIMENT TRANSPORT WITH IMPACTS OF AQUATIC VEGETATION

Aquatic vegetation plays an important role in the flow structure of open channels and thus changes the fate and the transport of sediment. This article proposes a three-dimensional turbulence model by introducing vegetation density and drag force into the control equations of water flow in the presence of vegetation. The model was used to calculate the impacts of submerged vegetation on the vertical profiles of longitudinal flow velocities, the changes of the depth-averaged flow velocities in a compound channel with emergent vegetation in the floodplain, the removal of suspended sediment from the channels by emergent vegetation, and the bed changes around and in a vegetated island. Numerical investigations show that aquatic vegetation retards flow in the vegetation zone, reduces the sediment transport capacity, and contributes to erosion on both sides of the vegetated island. Calculated results agree well with experimental results.

Power Flow Model for Medium-voltage Distribution Systems Considering Measurement and Structure Characteristics

Medium-voltage distribution systems(MVDSs)mainly consist of a feeder head,lines,distribution transformers,and the equivalent load or power supply interfaced with the distribution transformers.The information of such load or power supply can be measured via the three-wattmeter method(THM)and the two-wattmeter method(TWM).The measurements can be used to perform the control of the power supply and simulate the characteristics of the load,so the models of the load and the power supply need to consider the measurement characteristics.Existing research works on three-phase power flow(PF)just consider the measurement characteristics of THM.Hence,the PF equation of the bus measured via TWM is firstly built.Based on conventional measurements,an accurate and general model of the grounded and ungrounded slack bus is proposed.Furthermore,the influence arising from the connection type and angle shift of distribution transformers on the admittance matrix is considered,and thus a general three-phase transformer model is summarized,which is applicable for all the transformers mentioned herein.Finally,Newton's method is adopted to solve the PF calculation,and the performance of the proposed PF model is demonstrated through designed tests.

Sedimentation process of saturated sand under impact loading

The initial small inhomogeneity of saturated sand could be amplified during the sedimentation process after liquefaction, and cracks could be observed in the sand column. Layers of fine sand could also be found at the exact place where cracks developed and disappeared. The phenomena and the whole process were experimentally shown by X-rays images. To account for the phenomena, a linearized stability analysis of the sedimentation of saturated sand was conducted; however, it did not produce a satisfactory result. A three-phase flow model describing the transportation of fine sand is presented in this paper. It is shown that such a kind of erosion/deposition model was qualitatively in good agreement with the experimental observation.