Applications of a particle simulation approach

Kabakcı, İsmail
The thesis is intended to utilize a particle simulation approach, introduced for simple particles, for engineering problems in order to study and understand fluid behavior at molecular level. First, an improvement in force potential estimation is proposed for the original method, which offers notable accuracy increase in simulations in terms of determination of position and momentum trajectories. Afterwards, the improved method is applied to heat diffusion and unidirectional fluid flow simulations. Within the context of the approach, instantaneous velocities of particles are calculated using simple algebraic equations instead of solving differential equations. Equations are derived from Newton’s 2nd Law of Motion and Lennard-Jones Force Potential Theory. For interactions taking place between unlike particles, Lorentz-Berthelot Combination Rule is used. The method is checked in terms of probability density function of speed distribution, distribution of velocity vector components and pressures at equilibrium state. In the scope of diffusion dynamics, thermal characteristics of particles and volume are tracked in order to perform equilibrium analyses. Furthermore, thermal conductivity coefficient is calculated. Finally, the variation of density between particles is investigated under unidirectional flow condition. Simulation results give Maxwell-Boltzmann and Gaussian distribution functions in terms of speed and velocity components respectively. Results on pressure calculation compromise with the classical equation of state. Thermal conductivity coefficient agrees with the experimental data. According to the unidirectional fluid flow simulations, the results imply the tendency of particles to stay closer with increasing unidirectional flow velocity.


Validation of a particle simulation approach
Eneren, Şeyma Pinar; Çöker, Demirkan; Çıray, Cahit; Department of Aerospace Engineering (2016)
This thesis is intended to study the fluid behaviour with a new approach through the particle simulation technique. The fluid is considered to be under static conditions, and the activity of fluid particles is simulated. The method in the approach is mathematically exact. Instantaneous velocities are calculated with simple algebraic equations. Hence high efficiency in CPU time is achieved. In order to validate the method, the probability density function of the Maxwell-Boltzmann speed distribution and the p...
Application of spring analogy mesh deformation technique in airfoil design optimization
Yang, Yosheph; Özgen, Serkan; Department of Aerospace Engineering (2015)
In this thesis, an airfoil design optimization with Computational Fluid Dynamics (CFD) analysis combined with mesh deformation method is elaborated in detail. The mesh deformation technique is conducted based on spring analogy method. Several improvements and modifications are addressed during the implementation of this method. These enhancements are made so that good quality of the mesh can still be maintained and robustness of the solution can be achieved. The capability of mesh deformation is verified by...
Acceleration of molecular dynamics simulation for TERSOFF2 potential through reconfigurable hardware
Vargün, Bilgin; Erkoç, Şakir; Eminoğlu, Selim; Department of Micro and Nanotechnology (2012)
In nanotechnology, Carbon Nanotubes systems are studied with Molecular Dynamics Simulation software programs investigating the properties of molecular structure. Computational loads are very complex in these kinds of software programs. Especially in three body simulations, it takes a couple of weeks for small number of atoms. Researchers use supercomputers to study more complex systems. In recent years, by the development of sophisticated Field Programmable Gate Array (FPGA) Technology, researchers design s...
Investigation of effect of design and operating parameters on acoustophoretic particle separation via 3D device-level simulations
Sahin, Mehmet Akif; ÇETİN, BARBAROS; Özer, Mehmet Bülent (Springer Science and Business Media LLC, 2019-12-16)
In the present study, a 3D device-level numerical model is implemented via finite element method to assess the effects of design and operating parameters on the separation performance of a microscale acoustofluidic device. Elastodynamic equations together with electromechanical coupling at the piezoelectric actuators for the stress field within the solid parts, Helmholtz equation for the acoustic field within fluid, and Navier-Stokes equations for the fluid flow are coupled for the simulations. Once the zer...
Components of detector response function: Monte Carlo simulations and experiment
Pekoz, Rengin; Can, Cüneyt (Wiley, 2006-11-01)
Components of the response function of an HPGe detector for 32 keV incident photons (Ba K alpha x-rays) were studied using a Monte Carlo program. Physical mechanisms and the role of incident photons, detector x-rays, photoelectrons and Compton recoil and Auger electrons for each component were investigated. The position, intensity and shape of the components, particularly of the photoelectrons, were studied in detail. Two distinct components for photoelectron escape were identified by considering the fate o...
Citation Formats
İ. Kabakcı, “Applications of a particle simulation approach,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Aerospace Engineering., Middle East Technical University, 2019.