MD simulation app for iPhone and iPad

University of Ulsan, School of Mechanical Engineering,
MNTF(Micro/Nano-scale Thermo-Fluids Engineering) Lab.
http://home2.ulsan.ac.kr/user/nanofluid/


Please follow tutorials below for few example cases. All examples below assumes the initial states after the loading screen. (adjust Dt to see the result faster. Also try those with [WCA] and [Ideal])



1. Couette flow simulation

[Start] -wait until the system reaches to the equilibrium- [Couette] - wait until the system reaches to the steady state

(Instantaneous velocity profiles avaliable in the gray box at right-bottm)




2. Poiseuille flow simulation

[Start] - wait until the system reaches to the equilibrium - [Poiseuille]- wait until the system reaches to the steady state



3. Diffusion simulation

[Init3,4,5] - set target temperature around 250~350K - [start]



4. Freezing & crystallization simulation

[Init3,4,5] - set target temperature lower than 80K - [start]



5. More tips

! [Start] button sets Maxwell-Boltzmann velocity distributions to every fluid molecules.



! [L-J] is for VDW potential based on Argons molecular parameter, [WCA] is purely repulsive intermolecular interaction and [Ideal] neglects molecules size and collisions as the Ideal gas law assumes.



! You can increase time step (Dt) to make the simulations faster, but it may cause breakdown of simulations, and reset.



! When the simulation resets, target temperature and time step (Dt) sets to the lowest possible value.



! You can change target temperature during the simulations and adjust current temperature using thermostat.



! You can start simulations in various initial conditions using [Init] button



! [T/Tt] button sets thermostat to the system with the target temperature. "RED" tag means velocity scaling thermostat and "ORANGE" tag means Nose-Hoover thermostat.




***Molecular Dynamics in iPhone
Argon Fluid in 5nm Channel

In last two decades, the revolutionary advance of high-performance computing resources lead the Molecular Dynamics (MD) studies of atomistic level modeling in personal desktop computers. Now I am expanding MD platforms to the available powerful mobile computing devices (iPhone), and this may be the first attempt in the MD history.




Fluid flows in micron and nano - scale domains are frequently encountered in the components of micro electromechanical systems, microfluidic devices, and in computer hard drives. For example, for the hard-drive systems, distance between the head and media is on the order of tens of nanometers. Fluid flow in such small scales cannot be described using the continuum hypothesis. Molecular dynamics potentially can address those issues such as solid - fluid interfaces / interactions arising in the nano - scale regime. Furthermore, large scale simulations based on atomistic models may also address the transition from atomistic to continuum scale approaches

This is a molecular dynamics (MD) code (i2DMD) running on iPhone. This code has most features (but simplified for visualization & educational purpose) of actual MD code used for my publications in SCI journals listed in the information link. You can simulate Couette flow, Poiseuille flow, diffusion and Freezing of Argon in 5nm channel with periodic boundary conditions. I hope this sample code would help people to understand the nano-scale molecular