Resistance characteristics of paste pipeline flow in a pulse-pumping environment

Paste flow patterns and microscopic particle structures were studied in a pressurized environment generated by a pulse pump.Complex loop-pipe experiments and fluid-solid coupling-based simulations were conducted.The scanning electron microscopy technique was also applied.Results revealed that flow resistance is closely related to pipeline curvature and angle in a complex pipe network.The vertical downward-straight pipe-inclined downward combination was adopted to effectively reduce the loss in resistance along with reducing the number of bends or increasing the radius of bend curvature.The maximum velocity ratio and velocity offset values could quantitatively characterize the influences of different pipeline layouts on the resistance.The correlation reached 96%.Particle distribution and interparticle forces affected flow resistance.Uniform particle states and weak interparticle forces were conducive to steady transport.Pulse pump pressure led to high flow resistance.It could improve pipe flow stability by increasing flow uniformity and particle motion stability.These results can contribute to safe and efficient paste filling.

A model for coupling reservoir inflow and wellbore flow in fishbone wells

A coupling model is proposed in this paper by using the Green Function and Newman＇s product principle, and the solution method is provided here as well. This model can be used to describe the reservoir inflow and wellbore flow for fishbone wells in an unsteady flow or pseudo-steady flow state. A case study indicates that the bottom hole pressure declines quickly in the unsteady flow period which is very short. The pressure drop per unit time remains unchanged under the pseudo-steady flow conditions. The distribution of flow rate along the main wellbore shows a wave shape under the unsteady flow condition, and the flow rate distribution in each branch is similar. The flow rate distribution along the main wellbore is irregular ＂U＂ shaped under the pseudo-steady flow condition, and the space-symmetrical branches have the same flow distribution pattern. In the initial production period, the flow rate increases significantly as the length of branches and the angle between branches and the main wellbore increase. As the production continues, the length and angle of branches have only a slight effect on the flow in fishbone wells.

Numerical investigation of transitions in flow states and variation in aerodynamic forces for flow around square cylinders arranged inline

This study focuses on the transitions in flow states around two-, three-and four-inline square cylinders under the effect of Reynolds numbers at two different gap spacing values using the lattice Boltzmann method. For this purpose, Reynolds number is varied in the range 1–130 while two different values of spacing taken into account are gap spacing =2 and 5. Before going to actual problem, the code is tested for flow around a single square cylinder by comparing the results with experimental and numerical results of other researchers, and good agreement is found.The current numerical computations yield that for both spacing values and all combinations of cylinders there exist three different sates of flow depending on Reynolds numbers: steady state, transitional state and unsteady state. It is found that the range of Reynolds numbers for these flow states is different for both spacing values. At gap spacing =2 the range of Reynolds numbers for each flow state decreases by increasing the number of cylinders while at gap spacing =5 opposite trend is observed. The results also show that at gap spacing =2 the reduction in drag force is greater than the corresponding reduction at gap spacing =5. The maximum reduction in drag force is observed at Reynolds numbers =1 at both spacing values. Similarly, at both spacing values and all Reynolds numbers, the maximum reduction in drag force is observed for the case of four-inline square cylinders.

Numerical Simulation of Dense Gas-solid Two Phase Flow in a Steady-state Fluidized Bed

To investigate the influence of the furnace structure and inlet gas velocity on gas-solid two-phase flow states in the deposition furnace,FLUENT software was used to simulate dense gas-solid two-phase flow in a fluidized bed.The results show that the dispersed fluidized bed formed in the deposition furnace with a cone angle of 60°has the structure of"ring-nucleus"and longer gas retention time compared with the flat-bottom structure deposition furnace,which is beneficial to the preparation of the pyrolytic carbon coating materials with a uniform structure and excellent quality.Inlet gas velocity should be moderate,the slow inlet gas velocity leads to the chaos of the particle velocity distribution,which cannot form the ring-core flow structure.High inlet gas velocity leads to the back mixing of particles in the deposition furnace.In addition,as the inlet gas velocity increases,both the gas phase and the average particle velocity in the central area of the deposition furnace gradually increase,and the effect of the gas phase velocity is more obvious.

EFFECTS OF VASCULAR ZERO STRESS STATE ON PULSATILE BLOOD FOLW

In this paper,blood flow in artery was treated as the flow under equilibrium state (the steady flow under mean pressure) combined with the periodically small sulsatile flow.Based on vascular zero stress state ,the pulsatile strains according to the radial and axial displacements of blood vessel were obtained.With the use of Hooke's law,the pulsatile strains and the corresponding Cauchy stresses were connected,so the corresponding wall motion equations could be established here.By solving the linearized Navier Stokes equations,the analytic expressions of the blood flow velocities and the vascular displacements could be obtained,and the in fluence of the circumferential and axial stretch ratio on pulsatile blood flow and vascular motion was discussed in details.

A FINITE ELEMENT AND BOUNDARY ELEMENT METHOD OF NUMERICAL SIMULATION OF TWO DIMENSIONAL AND TWO PHASE FLOW

In this paper, an efficient finite element and boundary element method is presented for a two dimensional and two phase flow model with satisfactory results. So another method for solving reservoir simulation of two dimensional and two Phase flow is developed.