Numerical modeling and experimental measurements of water spray impact and transport over a cylinder

2006 ◽  
Vol 32 (1) ◽  
pp. 132-157 ◽  
Author(s):  
S.S. Yoon ◽  
P.E. DesJardin ◽  
C. Presser ◽  
J.C. Hewson ◽  
C.T. Avedisian
Keyword(s):  
Numerical Modeling ◽  
Experimental Measurements ◽  
Water Spray

The Role of Coulombic Forces in Quasi-Two Dimensional Electrochemical Deposition

1996 ◽  
Vol 451 ◽  
Author(s):  
G. Marshall ◽  
P. Mocskos ◽  
F. Molina ◽  
S. Dengra
Keyword(s):  
Numerical Modeling ◽  
Pattern Formation ◽  
Electrochemical Deposition ◽  
Growth Pattern ◽  
Stokes Equations ◽  
Fluid Motion ◽  
Navier Stokes ◽  
Experimental Measurements ◽  
Dimensionless Numbers ◽  
Navier Stokes Equations

ABSTRACTRecent work demonstrates the relevant influence of convection during growth pattern formation in thin-layer electrochemical deposition. Convection is driven mainly by coulombic forces due to local charges at the tip of the aggregation and by buoyancy forces due to concentration gradients. Here we study through physical experiments and numerical modeling the regime under which coulombic forces are important. In the experimental measurements fluid motion near the growing tips of the deposit is visualized with neutrally buoyant latex spheres and its speed measured with videomicroscope tracking techniques and image processing software. The numerical modeling consists in the solution of the 2D dimensionless Nernst-Planck equations for ion concentrations, the Poisson equation for the electric field and the Navier-Stokes equations for the fluid flow, and a stochastic growth rule for ion deposition. A new set of dimensionless numbers governing electroconvection dominated flows is introduced. Preliminary experimental measurements and numerical results indicate that in the electroconvection dominated regime coulombic forces increase with the applied voltage, and their influence over growth pattern formation can be assessed with the magnitude of the dimensionless electric Froude number. It is suggested that when this number decreases the deposit morphology changes from fractal to dense branching.

scholarly journals Fluid flow in the impulse valve of a hydraulic ram

2020 ◽  
Vol 3 (22) ◽  
Author(s):  
Wojciech Sobieski ◽  
Dariusz Grygo
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Modeling ◽  
Hydrodynamic Pressure ◽  
Water Velocity ◽  
Experimental Measurements ◽  
Ansys Fluent ◽  
Working Cycle ◽  
Numerical Studies ◽  
Minimum Force

The paper presents the results of a study investigating the equilibrium of forces acting on the closing element of the impulse valve in a water ram at the end of the acceleration stage. Acceleration is one of the three main stages in the working cycle of a water ram. In the first part of the paper, we estimated water velocity based on our earlier experimental measurements. We also calculated the minimum force required for closing the impulse valve. The second part of the paper discusses two variants of a numerical model, which was developed in ANSYS Fluent to determine the result-ant hydrodynamic pressure and, consequently, the forces acting on the head of the impulse valve at the end of the acceleration stage. The main aim of this research was to verify the applicability of numerical modeling in water ram studies. The present study was motivated by the fact that Computational Fluid Dynamics is very rarely applied to water rams. In particular, we have not found any numerical studies related to the equilibrium of forces acting on the closing element of the impulse valve in a water ram.

Experimental Measurements and Numerical Modeling Validation of Temperature Distribution in Tissue Medium During Short Pulse Laser Irradiation

2007 ◽  
Author(s):  
Ashim Dutta ◽  
Kyunghan Kim ◽  
Kunal Mitra ◽  
Zhixiong Guo
Keyword(s):  
Numerical Modeling ◽  
Heat Conduction ◽  
Temperature Distribution ◽  
Laser Beam ◽  
Pulse Laser ◽  
Short Pulse ◽  
Hyperbolic Heat Conduction ◽  
Experimental Measurements ◽  
Conduction Model ◽  
Short Pulse Laser

The objective of this paper is to analyze the temperature distributions and heat affected zone in skin tissue medium when irradiated with either a collimated or a focused laser beam from a short pulse laser source. Single-layer and three-layer tissue phantoms containing embedded inhomogeneities are used as a model of human skin tissue having subsurface tumor. Q-switched Nd:YAG laser is used in this study. Experimental measurements of axial and radial temperature distribution in the tissue phantom are compared with the numerical modeling results. For numerical modeling, the transient radiative transport equation is first solved using discrete ordinates method for obtaining the intensity distribution and radiative heat flux inside the tissue medium. Then the temperature distribution is obtained by coupling the bio-heat transfer equation with either hyperbolic non-Fourier or parabolic Fourier heat conduction model. The hyperbolic heat conduction equation is solved using MacCormack’s scheme with error terms correction. It is observed that experimentally measured temperature distribution is in good agreement with that predicted by hyperbolic heat conduction model. The experimental measurements also demonstrate that converging laser beam focused directly at the subsurface location can produce desired high temperature at that location as compared to that produced by collimated laser beam for the same laser parameters.

Terahertz Tomography of Low Contrast Objects: Algorithms and Experimental Measurements

2010 ◽  
Vol 5 (4) ◽  
pp. 91-97
Author(s):  
Valeriy V. Pickalov ◽  
Aleksandr L. Balandin ◽  
Dmitriy G. Rodionov ◽  
Maxim G. Vlasenko ◽  
Boris A. Knyazev
Keyword(s):  
Numerical Modeling ◽  
Iterative Algorithm ◽  
Experimental Methods ◽  
Experimental Measurements ◽  
Diffraction Tomography ◽  
Low Contrast ◽  
Type Algorithm ◽  
Thz Range

In this paper numerical modeling of tomography projections measurements is done and the iterative algorithm of diffraction tomography is developed for reconstruction of images of objects. Generalization of one of the most perspective algorithms of iterative type, – algorithm Gerchberg-Papoulis (G-P), from ray tomography to diffraction tomography, is evolved. Experimental methods of tomographical projections acquisition in a THz range are constructed

Sign in / Sign up

Export Citation Format

Share Document