A Growth Model For Ramified Electrochemical Deposition

1995 ◽  
Vol 407 ◽  
Author(s):  
Guillermo Marshall ◽  
Pablo Mocskos ◽  
Martin Olivella
Keyword(s):  
Growth Model ◽  
Electrochemical Deposition ◽  
Moving Boundary ◽  
Stokes Equations ◽  
Macroscopic Model ◽  
Navier Stokes ◽  
Discrete Version ◽  
Dimensionless Numbers ◽  
Navier Stokes Equations ◽  
Time Dependent Problem

ABSTRACTWe introduce a macroscopic model for the description of growth pattern formation in ramified electrochemical deposition. The theoretical model is formulated as a 2D time-dependent problem consisting in the Nernst-Planck equations for the concentration of the solute (cations and anions), coupled to a Poisson equation for the electrostatic potential and the Navier-Stokes equations for the solvent, with a moving boundary. A dimensional analysis is performed and a new set of dimensionless numbers governing the flow regime is derived. A 2D discrete version of these equations in a DBM scheme with a random moving boundary constitutes the computational model. We present numerical results which show that our growth model, with a proper variation of the set of dimensionless numbers, gives a reasonable picture of the interplay of the electroconvective, migration and diffusive motion of the ions near the growing tips.

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.

Coupled CFD/GNC Modeling for the Basic Finner Projectile with Closed Loop

2014 ◽  
Vol 541-542 ◽  
pp. 1478-1482
Author(s):  
Ke Xi ◽  
Chao Yan ◽  
Yu Huang ◽  
Wen Wang
Keyword(s):  
Closed Loop ◽  
Moving Boundary ◽  
Stokes Equations ◽  
Engineering Application ◽  
Flight Simulation ◽  
Navier Stokes ◽  
Control Law ◽  
Navier Stokes Equations ◽  
Motion Equations ◽  
Flow Solver

The virtual flight simulation of the Basic Finner projectile has been investigated through coupling solving unsteady Navier-Stokes equations, rigid-body six degree-of-freedom motion equations, guidance, navigation and control law. The flow solver uses a finite-volume method based on structure grid with dual time stepping, the chimera method is used to simulate relative motions, the fourth-order Runger-Kutta method is used to solve the motion equations. A closed loop feedback control law with PID control is required for the elevator to attain the commanded deflection. The predictions show that the PID parameters for the controller must be correctly selected to obtain the proper response. Simulation results show that the virtual flight simulation platform that we developed is capable of solving the complicated unsteady flows with moving boundary, has a strong applicability to engineering application.

CFD Transonic Trajectory Predictions of Three-Store Ripple Release Using Chimera Method

2014 ◽  
Vol 513-517 ◽  
pp. 4490-4493 ◽  
Author(s):  
Ke Xi ◽  
Chao Yan
Keyword(s):  
Moving Boundary ◽  
Stokes Equations ◽  
Unsteady Flows ◽  
Rigid Body Dynamics ◽  
Navier Stokes ◽  
Separation Problem ◽  
Navier Stokes Equations ◽  
Body Dynamics ◽  
Multi Body ◽  
Good Agreement

The complicated unsteady flows with moving boundary were simulated numerically by coupling solving unsteady compressible Navier-Stokes equations and 6DOF rigid-body dynamics equations. The Chimera grid technology was used to handle the relative motion. The three-store ripple release of the wing-store configuration was simulated using this method. The computational results are in good agreement with data from other literature, showing that the method used has a strong applicability to complex multi-body separation problem.

scholarly journals Directional Water Wicking on a Metal Surface Patterned by Microchannels

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 490
Author(s):  
Nima Abbaspour ◽  
Philippe Beltrame ◽  
Marie-Christine Néel ◽  
Volker P. Schulz
Keyword(s):  
Contact Angle ◽  
Stokes Equations ◽  
Industrial Applications ◽  
Type Structure ◽  
Navier Stokes ◽  
Small Space ◽  
Dimensionless Numbers ◽  
Navier Stokes Equations ◽  
Static Contact ◽  
Insight Into

This work focuses on the simulation and experimental study of directional wicking of water on a surface structured by open microchannels. Stainless steel was chosen as the material for the structure motivated by industrial applications as fuel cells. Inspired by nature and literature, we designed a fin type structure. Using Selective Laser Melting (SLM) the fin type structure was manufactured additively with a resolution down to about 30 μm. The geometry was manufactured with three different scalings and both the experiments and the simulation show that the efficiency of the water transport depends on dimensionless numbers such as Reynolds and Capillary numbers. Full 3D numerical simulations of the multiphase Navier-Stokes equations using Volume of Fluid (VOF) and Lattice-Boltzmann (LBM) methods reproduce qualitatively the experimental results and provide new insight into the details of dynamics at small space and time scales. The influence of the static contact angle on the directional wicking was also studied. The simulation enabled estimation of the contact angle threshold beyond which transport vanishes in addition to the optimal contact angle for transport.

Sign in / Sign up

Export Citation Format

Share Document