scholarly journals Unsteady-Flow Velocity Variations in and near An Embayment

1994 ◽  
Vol 38 ◽  
pp. 703-708 ◽  
Author(s):  
Haizhou TU ◽  
Nobuyuki TAMAI ◽  
K. KAN
Keyword(s):  
Unsteady Flow ◽  
Flow Velocity ◽  
Velocity Variations

Experimental Study on the Piping Erosion Mechanism of Gap-Graded Soils Under a Supercritical Hydraulic Gradient

2021 ◽  
Author(s):  
Liang Chen ◽  
Yu Wan ◽  
Jian-Jian He ◽  
Chun-Mu Luo ◽  
Shu-fa Yan ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Unsteady Flow ◽  
Relative Density ◽  
Flow Velocity ◽  
Steady Flow ◽  
Fine Particle ◽  
Failure Process ◽  
Hydraulic Gradient ◽  
Particle Content ◽  
Piping Erosion

Abstract Seepage-induced piping erosion is observed in many geotechnical structures. This paper studies the piping mechanism of gap-graded soils during the whole piping erosion failure process under a supercritical hydraulic gradient. We define the supercritical ratio Ri and study the change in the parameters such as the flow velocity, hydraulic conductivity, and fine particle loss with Ri. Under steady flow, a formula for determining the flow velocity state of the sample with Ri according to the fine particle content and relative density of the sample was proposed; during the piping failure process, the influence of Rimax on the rate at which the flow velocity and hydraulic conductivity of the sample increase as Ri decreases was greater than that of the initial relative density and the initial fine particle content of the sample. Under unsteady flow, a larger initial relative density corresponds to a smaller amplitude of increase in the average value of the peak flow velocity with increasing Ri. Compared with the test under steady flow, the flow velocity under unsteady flow would experience abrupt changes. The relative position of the trend line L of the flow velocity varying with Ri under unsteady flow and the fixed peak water head height point A under steady flow were related to the relative density of the sample.

scholarly journals Mesenteric flow velocity variations as a function of angle of insonation

1990 ◽  
Vol 11 (5) ◽  
pp. 688-694 ◽  
Author(s):  
Robert J. Rizzo ◽  
Gail Sandager ◽  
Patricia Astleford ◽  
Kathleen Payne ◽  
Linda Peterson-Kennedy ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Velocity Variations

341 A Study of Simultaneous Measurement of Vocal Fold Vibrations and Flow Velocity Variations Just Above the Glottis

2006 ◽  
Vol 2006 (0) ◽  
pp. _341-1_-_341-6_
Author(s):  
Shiro ARII ◽  
Hideyuki KATAOKA ◽  
Yoshitaka OCHIAI ◽  
Kensaku HASEGAWA ◽  
Toyohiko SUZUKI ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Simultaneous Measurement ◽  
Vocal Fold ◽  
Velocity Variations

Simulation of Simplified Three-Dimensional Space Flow Velocity Field in Reservoir on the Condition of Unsteady Flow and its Application

2012 ◽  
Vol 203 ◽  
pp. 514-518
Author(s):  
Shi Ping Fan ◽  
Jian Ming Yang ◽  
Min Quan Feng ◽  
Bang Min Zheng
Keyword(s):  
Numerical Calculation ◽  
Velocity Field ◽  
Flow Field ◽  
Unsteady Flow ◽  
Flow Velocity ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Flow Velocity Field ◽  
Flood Period ◽  
Three Dimensional Space

In view of the complexity of the conventional simulation calculation method of three-dimensional flow field for the reservoir, and to analysis of the change of the reservoir’s flow field in flood period, in this paper, based on the unsteady flow numerical calculation, the simulation method for three-dimensional space flow velocity field of the reservoir in flood period was studied and applied to the Wenyuhe Reservoir. First refining the actual extraction of grid, and then having an unsteady flow numerical calculation for the reservoir, finally through layering and stripping the grid, three-dimensional space flow velocity field the reservoir on the condition of unsteady flow has been studied. The results showed that the reservoir velocity along the flow direction is becoming smaller, and surface velocity is fast; with the flow increase gradually, the unsteady flow has a great effect on the flow field of the reservoir’s concave bank. The grid can at will encryption, so the calculation precision can be effectively controlled and the process of simulation is easy to be programmed. The research results can simplify the complexity of the reservoir for three-dimensional numerical simulation, and up to providing theoretical support for reservoir flood control.

scholarly journals Investigation on the Drag Coefficient of the Steady and Unsteady Flow Conditions in Coarse Porous Media

2021 ◽  
Author(s):  
Hadi Norouzi ◽  
Jalal Bazargan ◽  
Faezah Azhang ◽  
Rana Nasiri
Keyword(s):  
Reynolds Number ◽  
Porous Media ◽  
Friction Coefficient ◽  
Unsteady Flow ◽  
Drag Coefficient ◽  
Flow Velocity ◽  
Hydraulic Gradient ◽  
Flow Conditions ◽  
Porous Media Equations ◽  
Unsteady Flow Condition

Abstract The study of the steady and unsteady flow through porous media and the interactions between fluids and particles is of utmost importance. In the present study, binomial and trinomial equations to calculate the changes in hydraulic gradient (i) in terms of flow velocity (V) were studied in the steady and unsteady flow conditions, respectively. According to previous studies, the calculation of drag coefficient (Cd) and consequently, drag force (Fd) is a function of coefficient of friction (f). Using Darcy-Weisbach equations in pipes, the hydraulic gradient equations in terms of flow velocity in the steady and unsteady flow conditions, and the analytical equations proposed by Ahmed and Sunada in calculation of the coefficients a and b of the binomial equation and the friction coefficient (f) equation in terms of the Reynolds number (Re) in the porous media, equations were presented for calculation of the friction coefficient in terms of the Reynolds number in the steady and unsteady flow conditions in 1D (one-dimensional) confined porous media. Comparison of experimental results with the results of the proposed equation in estimation of the drag coefficient in the present study confirmed the high accuracy and efficiency of the equations. The mean relative error (MRE) between the computational (using the proposed equations in the present study) and observational (direct use of experimental data) friction coefficient for small, medium and large grading in the steady flow conditions was equal to 1.913, 3.614 and 3.322%, respectively. In the unsteady flow condition, the corresponding values of 7.806, 14.106 and 10.506 % were obtained, respectively.

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