Molecular Dynamic Computer Simulation Models for Teaching Thermodynamic Principles

Modern mechanical engineers need to learn more than the traditional classical approaches to thermodynamics and heat transfer. Matter is comprised of molecules and in many situations the behavior of these molecules may be modeled using hard spheres whose motion is governed by Newtonian mechanics. This is particularly true in those situations involving relatively low density gases, that are valuable in introducing the concepts of thermodynamics. This paper presents some models that have been developed using simple-to-use software that students can handle in a time-efficient way during class-room situations, using only Newtonian Mechanics. Experience indicates that students have many conceptual difficulties when studying engineering thermodynamics. Simple molecular dynamic approaches promise to give students a more intuitive understanding of these thermal areas.

Molecular Dynamic Computer Simulation of Thin Film's Heat Dissipation Rate

Heat dissipation rate of the thin film is theoretically related to the thickness of the film. As the film grows on a substrate of constant temperature, the heat dissipation rate would be lower when the film becomes thicker. It is difficult to observe rate change during the film growth through experiment. With MD simulation, this rate can be "observed". A system including Platinum substrate at constant temperature 300K is setup. The constant temperature is obtained by Phantom method.The average temperature of aluminum thin film is 600K. For various thickness of the film: 3.656nm, 5.302nm, and 7.567nm. The average temperature decays exponentially. Through the simple equation T=(T0-Ts)exp(-kt/d2PCp)+Ts, the dissipation rate should follow the parameter R=k/d2PCp and the parameter α=k/£Cp is the thermal diffusivity. It is observed that the thermal diffusivity increases with film thickness increases.

Molecular-Dynamic Computer Simulation Study of Structural and Transport Properties of Some Amorphous Alloys

Here we present the molecular-dynamics computer simulation for a few systems of Ni1−xPx (x=0.2,0.25), Fe1−xPx (x=0.24), and Fe1−xBx (x=0.15) to explore the dynamic phase transformation from liquid to amorphous state through rapid quenching and the structure of these alloys at atomic level. The truncated Morse potential has been used to model the interaction between the atoms. The results of computer simulation for the pair correlation function for these systems reveal some interesting features of the corresponding alloy going from the melt to amorphous state through fast cooling. Finally the analysis of Voronoy polyhedron statistic leads us to propose possible models for the structure at atomic level for these alloys in the amorphous state. For the Ni75P25 system it is also revealed that the metastable state depends on the method of preparation of the sample.