Numerical Simulation of Water Transport through Vessel Perforation Plates

2012 ◽  
Vol 195-196 ◽  
pp. 645-650
Author(s):  
Qi Chen ◽  
Fang Xu ◽  
Qin Lin Ai ◽  
Jiao Liao Chen
Keyword(s):  
Fluid Dynamics ◽  
Flow Characteristics ◽  
Substantial Effect ◽  
Microscopic Structure ◽  
Water Conductivity ◽  
Flow Equations ◽  
Perforation Plate ◽  
Calculation Results ◽  
Flow Through ◽  
Perforation Plates

The structure of perforation plate had a substantial effect on the water conductivity of plant vessels. As the microscopic structure of vessel and perforation plate is highly complex, it is very difficult to numerically solve the flow equations. The effects of perforation plate structure on water flow in plant xylem vessels were studied using CFD (computational fluid dynamics) approach, the calculation results were used to estimate the effects of the perforation plate on conductance. Results showed that simple plate provided less resistance than scalariform plate. The resistance to flow through the perforation plate increased as the plate angle increased (giving same number of pores). Increasing the pore size would reduce the resistance along the modeled vessel. The results also showed that gravity had hardly effect on flow characteristics in micro vessels of plant and nearly can be neglected.

scholarly journals A Simple Transient Poiseuille-Based Approach to Mimic the Womersley Function and to Model Pulsatile Blood Flow

Dynamics ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 9-17
Author(s):  
Andrea Natale Impiombato ◽  
Giorgio La Civita ◽  
Francesco Orlandi ◽  
Flavia Schwarz Franceschini Zinani ◽  
Luiz Alberto Oliveira Rocha ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Boundary Conditions ◽  
Quadratic Function ◽  
Pulsatile Blood Flow ◽  
Flow Through ◽  
Simplified Analysis ◽  
Function Models ◽  
Flow Reversals

As it is known, the Womersley function models velocity as a function of radius and time. It has been widely used to simulate the pulsatile blood flow through circular ducts. In this context, the present study is focused on the introduction of a simple function as an approximation of the Womersley function in order to evaluate its accuracy. This approximation consists of a simple quadratic function, suitable to be implemented in most commercial and non-commercial computational fluid dynamics codes, without the aid of external mathematical libraries. The Womersley function and the new function have been implemented here as boundary conditions in OpenFOAM ESI software (v.1906). The discrepancy between the obtained results proved to be within 0.7%, which fully validates the calculation approach implemented here. This approach is valid when a simplified analysis of the system is pointed out, in which flow reversals are not contemplated.

scholarly journals BACH FLOWS OF PRODUCT MANIFOLDS

2012 ◽  
Vol 09 (05) ◽  
pp. 1250039 ◽  
Author(s):  
SANJIT DAS ◽  
SAYAN KAR
Keyword(s):  
Dynamical System ◽  
Fixed Point ◽  
Ricci Flow ◽  
Flow Characteristics ◽  
Geometric Flow ◽  
Flow Equations ◽  
First Order ◽  
Bach Tensor ◽  
Point Condition ◽  
Future Work

We investigate various aspects of a geometric flow defined using the Bach tensor. First, using a well-known split of the Bach tensor components for (2, 2) unwarped product manifolds, we solve the Bach flow equations for typical examples of product manifolds like S2 × S2, R2 × S2. In addition, we obtain the fixed-point condition for general (2, 2) manifolds and solve it for a restricted case. Next, we consider warped manifolds. For Bach flows on a special class of asymmetrically warped 4-manifolds, we reduce the flow equations to a first-order dynamical system, which is solved exactly to find the flow characteristics. We compare our results for Bach flow with those for Ricci flow and discuss the differences qualitatively. Finally, we conclude by mentioning possible directions for future work.

Theoretical and Experimental Characterization of Emulsion Flow in a Cavity Transfer Mixer

2003 ◽  
Author(s):  
A. H. Raza ◽  
R. A. Lai-Fook ◽  
C. J. Lawrence
Keyword(s):  
Flow Characteristics ◽  
Axial Direction ◽  
Solution Procedure ◽  
Modes Of Operation ◽  
Flow Equations ◽  
Recirculating Flow ◽  
Rectangular Pattern ◽  
Mean Pressure ◽  
Emulsion Processing ◽  
Dependent Flow

A theoretical model of time-dependent flow based on Reynolds equation using emulsion processing in a Cavity Transfer Mixer (CTM) has been developed in Mathematica and is presented in this work. It is a continuum model, which allows the study of materials undergoing rapid deformation. The flow of a fluid in a CTM is examined using a finite difference analysis (FDA) to solve the flow equations for an unwound section with cavities arranged in a rectangular pattern. Periodic boundary conditions are included in the model to predict the pressure distribution, which allows subsequent determination of the flow field. The solution procedure gives a smooth function for the pressure field, with equal pressures at the boundaries in the y-direction and an overall mean pressure gradient in the x-direction. Once the pressure has been found, several flow properties follow directly. The flow in the downstream axial direction is seen to consist of purely pressure-driven flow. In contrast, the flow in the cross-cavity direction is a recirculating flow driven by the drag velocity of the moving rotor surface. These two flows taken together combine into a helical flow travelling through the cavity. Because of this, there is likely to bre a high degree of laminar and distributive flow in this type of machine. The experimental part of this work addresses the processing of an emulsion in the CTM when it is run under batch and continuous modes of operation. The flow characteristics have been studied for varying rotor speeds of 0 rpm, 16 rpm, 32 rpm, 48 rpm and 64 rpm. Also studied were the changes that the emulsion exhibits along the mixer length and with time in the mixer. The experiments indicate that increase in the rotational speed causes the viscosity to reduce systematically in both batch and continuous modes of operation.

Effect of Feedback Control on the Power Consumption of Induced-Strain Actuators

2000 ◽  
Author(s):  
Sriram Chandrasekaran ◽  
Douglas K. Lindner ◽  
Don Leo
Keyword(s):  
Structural Control ◽  
Power Flow ◽  
Reactive Power ◽  
Flow Characteristics ◽  
Control Laws ◽  
The Real ◽  
Reactive Power Flow ◽  
Flow Through ◽  
Sinusoidal Disturbance ◽  
A Current

Abstract In this paper we study the closed loop power flow characteristics between a controlled piezoelectric actuator and a current controlled drive amplifier for two different structural control laws. We determine the real and reactive power flow through the structure and actuator into the amplifier when the structure is excited with a sinusoidal disturbance force under both control laws. The dependence of the real and reactive components of the power on the material properties of the actuator, structure and the configuration of the controller is presented. These real and reactive power estimates are useful for sizing the drive amplifier for the actuator.

scholarly journals Free-surface flow simulations for discharge-based operation of hydraulic structure gates

2013 ◽  
Vol 16 (1) ◽  
pp. 189-206 ◽  
Author(s):  
C. D. Erdbrink ◽  
V. V. Krzhizhanovskaya ◽  
P. M. A. Sloot
Keyword(s):  
Free Surface ◽  
Hydraulic Structure ◽  
Flow Characteristics ◽  
Surface Flow ◽  
Water Levels ◽  
Surface Model ◽  
Local Flow ◽  
Gate Operation ◽  
Flow Equations ◽  
Flow Simulations

We combine non-hydrostatic flow simulations of the free surface with a discharge model based on elementary gate flow equations for decision support in the operation of hydraulic structure gates. A water level-based gate control used in most of today's general practice does not take into account the fact that gate operation scenarios producing similar total discharged volumes and similar water levels may have different local flow characteristics. Accurate and timely prediction of local flow conditions around hydraulic gates is important for several aspects of structure management: ecology, scour, flow-induced gate vibrations and waterway navigation. The modelling approach is described and tested for a multi-gate sluice structure regulating discharge from a river to the sea. The number of opened gates is varied and the discharge is stabilized with automated control by varying gate openings. The free-surface model was validated for discharge showing a correlation coefficient of 0.994 compared to experimental data. Additionally, we show the analysis of computational fluid dynamics (CFD) results for evaluating bed stability and gate vibrations.

scholarly journals Derivation of Global Parametric Performance of Mixed Flow Hydraulic Turbine Using CFD

1970 ◽  
Vol 7 ◽  
pp. 60-64 ◽  
Author(s):  
Ruchi Khare ◽  
Vishnu Prasad Prasad ◽  
Sushil Kumar
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Solutions ◽  
Guide Vane ◽  
Hydraulic Turbine ◽  
Francis Turbine ◽  
Mixed Flow ◽  
Flow Equations ◽  
Laboratory Setup ◽  
Wide Range

The testing of physical turbine models is costly, time consuming and subject to limitations of laboratory setup to meet International Electro technical Commission (IEC) standards. Computational fluid dynamics (CFD) has emerged as a powerful tool for funding numerical solutions of wide range of flow equations whose analytical solutions are not feasible. CFD also minimizes the requirement of model testing. The present work deals with simulation of 3D flow in mixed flow (Francis) turbine passage; i.e., stay vane, guide vane, runner and draft tube using ANSYS CFX 10 software for study of flow pattern within turbine space and computation of various losses and efficiency at different operating regimes. The computed values and variation of performance parameters are found to bear close comparison with experimental results.Key words: Hydraulic turbine; Performance; Computational fluid dynamics; Efficiency; LossesDOI: 10.3126/hn.v7i0.4239Hydro Nepal Journal of Water, Energy and EnvironmentVol. 7, July, 2010Page: 60-64Uploaded date: 31 January, 2011

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