arXiv subjects

Sumith Yesudasan

Publications and source records attributed to Sumith Yesudasan.

10 recordsLinked to original sources

arXiv2024

Evaporation Characteristics of Heat Pipes with Sub-Critical Nanopores

This study explores heat transfer mechanisms in heat pipes with sub-critical nanopores using coarse-grained molecular dynamics (CGMD) simulations, aiming to enhance thermal management in nanoscale applications. With the increasing need for efficient cooling solutions in microelectronics and high-performance computing, nanoporous heat pipes have gained attention due to their high thermal conductivity and passive operation. This research evaluates the effects of pore size, temperature gradients, and water fill ratios on the heat transfer efficiency of heat pipes with 2 nm and 3 nm diameter nanopores. The results indicate that larger temperature gradients significantly enhance heat transfer rates, while filled heat pipes perform better than medium-filled ones, primarily due to more effective phase change and fluid flow dynamics. Notably, the 2 nm filled models show improved performance over the 3 nm models, suggesting an optimal balance between capillary action and fluid resistance at smaller pore sizes. The study also reveals that in sub-critical nanopores, surface-driven flows are more effective than traditional wicking, underscoring the role of surface interactions in optimizing heat transfer. These findings provide critical insights for designing and optimizing nanoporous heat pipes, offering practical guidance for developing more efficient thermal management systems in electronics cooling and other applications.

cond-mat.mes-hall↗

arXiv2022

Critical Diameter for Continuous Evaporation is between 3 nm and 4 nm for Hydrophilic Nanopores

Evaporation studies of water using classical molecular dynamics simulations are largely limited due to their high computational expense. This study addresses that issue by developing coarse-grained molecular dynamics models based on Morse potential. Models are optimized based on multi-temperature and at room temperature using machine learning techniques like genetic algorithm, Nelder-Mead algorithm, and Strength Pareto Evolutionary Algorithm. The multi-temperature based model named as Morse-D is found to be more accurate than single temperature model in representing the water properties at higher temperatures. Using this Morse-D water model, evaporation from hydrophilic nanopores with pore diameter varying from 2 nm to 5 nm is studied. Our results show that the critical diameter to initiate continuous evaporation at nanopores lies between 3 nm and 4 nm. A maximum heat flux of 21.3 kW/cm2 is observed for a pore diameter of 4.5 nm and a maximum mass flow rate of 16.2 ng/s for a pore diameter of 5 nm. The observed heat flux is an order of magnitude times larger than the currently reported values from experiments in the literature for water, which indicates that we need to focus on nanoscale evaporation to enhance the critical heat flux.

cond-mat.soft↗

arXiv2021

Generating and Managing Strong Passwords using Hotel Mnemonic

Weak passwords and availability of supercomputers to password crackers make the financial institutions and businesses at stake. This calls for use of strong passwords and multi factor authentication for secure transactions. Remembering a long and complex password by humans is a daunting task and mnemonic has helped to mitigate this situation to an extent. This paper discusses creating and using long random password and storing them securely using a hybrid strategy of hash-encryption method. The hash function uses a mnemonic password based on the hotel names and other characteristics like room number, floor number and breakfast meal preferences to generate the encryption key. The random strong password can be then encrypted using the key and stored safely. A computer program named Hector is developed which demonstrates these steps and can be used to generate and store the passwords.

cs.CR↗

arXiv2019

Extended MARTINI Water Model for Heat Transfer Studies

The computationally efficient classical MARTINI model is extended to simulate heat transfer simulations of water. The current MARTINI model, variations of it and other coarse grain water models focus on reproducing the thermodynamic properties below room temperature, hence making them unsuitable for studying high temperature simulations especially evaporation at 100 °C. In this work, the MARTINI model is reparametrized using a combination of Genetic Algorithm, Artificial Neural Network and Nelder-Mead optimization technique to match the phase equilibrium properties of water. The reparametrized model (MARTINI-E) accurately reproduces density, enthalpy of vaporization and surface tension at 100°C and outperforms other leading coarse grain water models. The model is also validated using the energy conservation and enthalpy change due to latent heat in a lamellar system. This new water model can be used for simulating phase change phenomena, thin film evaporation and other energy transport mechanisms accurately.

physics.comp-ph↗

arXiv2018

Multiscale Network Model for Fibrin Fibers and Fibrin Clot with Protofibril Binding Mechanics

The multiscale behavior of the individual fibrin fibers and fibrin clots is modeled by coupling atomistic simulation data and microscopic experimental data. We propose a protofibril element made up of nonlinear spring network, constructed based on the molecular simulation and atomic force microscopy results to simulate the force extension behavior of fibrin fibers. This new network model also accounts for the complex interaction of protofibrils with each other, effect of presence of solvent, Coulombic attraction and other binding forces. The network model is applied to simulate the force extension behavior of single fibrin fiber from atomic force microscopy experiments and shows good agreement. Thus validated fibrin fiber network model is then combined with a modified version of Arruda-Boyce eight chain model to estimate the force extension behavior of continuum level fibrin clot, which shows very good correlation. The results show that this network model is able to predict the behavior of fibrin fibers as well as fibrin clot at small strains, large strains and even closer to the break strain. We use the network model to explain why the fibrin clots and fibers doesn't behave like a worm like chain, instead behaves like a nonlinear spring.

physics.bio-ph↗

arXiv2018

A Direct Two-Dimensional Pressure Formulation in Molecular Dynamics

Two-dimensional (2D) pressure field estimation in molecular dynamics (MD) simulations has been done using three-dimensional (3D) pressure field calculations followed by averaging, which is computationally expensive due to 3D convolutions. In this work, we develop a direct 2D pressure field estimation method which is much faster than 3D methods without losing accuracy. The method is validated with MD simulations on two systems: a liquid film and a cylindrical drop of argon suspended in surrounding vapor.

physics.chem-ph↗

arXiv2018

Recent Advances in Computational Modeling of Thrombosis

The study of thrombosis is crucial to understand and develop new therapies for diseases like deep vein thrombosis, diabetes related strokes, pulmonary embolism etc. The last two decades have seen an exponential growth in studies related to the blood clot formation using computational tools and through experiments. Despite of this growth, the complete mechanism behind thrombus formation and hemostasis is not known yet. The computational models and methods used in this context are diversified into different spatiotemporal scales, yet there is no single model which can predict both physiological and mechanical properties of the blood clots. In this review, we will attempt to list out all major strategies attempted by researchers so far to model the blood clot formation using existing computational techniques. This review classifies them into continuum level, system level, discrete particles and multi-scale methods. We will also discuss the strength and weakness of various methods and possible future directions in which the computational blood clot research can thrive.

physics.med-ph↗

arXiv2017

Coarse Grain Molecular Dynamics Simulation of Fibrin Polymerization

Studies suggests that patients with deep vein thrombosis and diabetes often have hy-per coagulable blood plasma leading to higher chances of forming thromboembolisms by the rupture of blood clots, which may lead to stroke and death. Despite the advances in the field of blood clot formation and lysis research, the change in mechanical properties and its impli-cation into the formation of thromboembolisms in platelet poor plasma is poorly understood. In this paper, we present a new computational method to simulate fibrin clot formation using molecular simulations. With an effective combination of reactive molecular dynamics con-cept and coarse graining principle, we have utilized the reactive coarse grain molecular dy-namics to predict the complex network formation of fibrin clots and the branching of the fi-brins. The heavy 340 kDa fibrinogen is converted into a simple spring-bead coarse grain sys-tem with 9 beads, and using our customized reactive potentials, we simulated the formation of the fibrin clot. Thus, formed fibrin clot agrees with the experimental results qualitatively, and to our best knowledge this is the first kind of molecular polymerization study of fibrin clot which can lead to improve our understanding about blood clot formation and its relation-ship with mechanical properties.

physics.bio-ph↗

arXiv2017

Molecular Dynamics Simulations Indicate that Deoxyhemoglobin, Oxyhemoglobin, Carboxyhemoglobin, and Glycated Hemoglobin under Compression and Shear Exhibit an Anisotropic Mechanical Behavior

We developed a new mechanical model for determining the compression and shear mechanical behavior of four different hemoglobin structures. Previous studies on hemoglobin structures have focused primarily on overall mechanical behavior; however, this study investigates the mechanical behavior of hemoglobin, a major constituent of red blood cells (RBCs), using steered molecular dynamics (SMD) simulations to obtain anisotropic mechanical behavior under compression and shear loading conditions. Four different configurations of hemoglobin molecules were considered: deoxyhemoglobin (deoxyHb), oxyhemoglobin (HbO2), carboxyhemoglobin (HbCO), and glycated hemoglobin (HbA1C). The SMD simulations were performed on the hemoglobin variants to estimate their unidirectional stiffness and shear stiffness. Although hemoglobin is structurally denoted as a globular protein due to its spherical shape and secondary structure, our simulation results show a significant variation in the mechanical strength in different directions (anisotropy) and also a strength variation among the four different hemoglobin configurations studied. The glycated hemoglobin molecule possesses an overall higher compressive mechanical stiffness and shear stiffness when compared to deoxyhemoglobin, oxyhemoglobin, and carboxyhemoglobin molecules. Further results from the models indicate that the hemoglobin structures studied possess a soft outer shell and a stiff core based on stiffness.

physics.bio-ph↗

arXiv2016

Electromagnetically Induced Distortion of a Fibrin Matrix with Embedded Microparticles

Blood clots occur in the human body when they are required to prevent bleeding. In pathological states such as diabetes and sickle cell disease, blood clots can also form undesirably due to hypercoagulable plasma conditions. With the continued effort in developing fibrin therapies for potential life-saving solutions, more mechanical modeling is needed to understand the properties of fibrin structures with inclusions. In this study, a fibrin matrix embedded with magnetic micro particles (MMPs) was subjected to a magnetic field to determine the magnitude of the required force to create plastic deformation within the fibrin clot. Using finite element (FE) analysis, we estimated the magnetic force from an electromagnet at a sample space located approximately 3 cm away from the coil center. This electromagnetic force coupled with gravity was applied on a fibrin mechanical system with MMPs to calculate the stresses and displacements. Using appropriate coil parameters, it was determined that application of a magnetic field of 730 A/m on the fibrin surface was necessary to achieve an electromagnetic force of 36 nN (to engender plastic deformation).

physics.bio-ph↗