arXiv subjects

Rajkumar Sarma

Publications and source records attributed to Rajkumar Sarma.

5 recordsLinked to original sources

arXiv2025

Strong thermoelectric response of nanoconfined weak electrolytes

When dissolved, weak electrolytes only partially dissociate into ions in a temperature-dependent process. We show herein that such incomplete dissociation yields an enormous thermoelectric response in an electrolyte-filled nanochannel along which a temperature gradient is applied. For this purpose, an extended version of the Nernst-Planck equations is developed that takes into account the temperature-dependent dissociation-association equilibrium. The results indicate that in this way, Seebeck coefficients can be achieved that outperform all previously reported values.

cond-mat.soft↗

arXiv2023

Giant thermoelectric response of confined electrolytes with thermally activated charge carrier generation

The thermoelectric response of thermally activated electrolytes (TAE) in a slit channel is studied theoretically and by numerical simulations. The term TAE refers to electrolytes whose charge carrier concentration is a function of temperature, as recently suggested for ionic liquids and highly concentrated aqueous electrolyte solutions. Two competing mechanisms driving charge transport by temperature gradients are identified. For suitable values of the activation energy that governs the generation of charge carriers, a giant thermoelectric response is found, which could help explaining recent experimental results for nanoporous media infiltrated with TAEs.

cond-mat.soft↗

arXiv2020

Marangoni instability in a viscoelastic binary film with cross-diffusive effect

The viscoelastic fluids are usually the blends of a polymeric solute and a Newtonian solvent. In the presence of a temperature gradient, stratification of these solutes can take place via the Soret effect. Here, we investigate the classical Marangoni instability problem for a thin viscoelastic film considering this binary aspect of the fluid. The film, bounded above by a deformable free surface, is subjected to heating from below by a solid substrate. Linear stability analysis performed numerically for perturbations of finite wavelength (short-wave perturbations) reveals that both monotonic and oscillatory instabilities can emerge in this system. The interaction between the thermocapillary and solutocapillary forces in the presence of Soret diffusion is found to give rise to two different oscillatory instabilities, of which one mode was overlooked previously, even for the Newtonian binary mixtures. As a principal result of this work, we provide a complete picture of the susceptibility to different instability modes based on the model parameter values. Finally, an approximate model is developed under the framework of long-wave analysis, which can qualitatively depict the stability behaviour of the system without numerically solving the problem.

physics.flu-dyn↗

arXiv2020

Thermosolutal Marangoni instability in a viscoelastic liquid film: Effect of heating from the free surface

We study the Marangoni instability in a thin polymeric liquid film heated from the free surface. Polymeric solutions are usually the binary mixture of a Newtonian solvent with polymeric solute and exhibit viscoelastic behaviour. In the presence of a temperature gradient, stratification of these polymeric solutes can take place via the Soret effect, which may give rise to the solutocapillary effect at the free surface. Considering the Soret effect and incorporating the effects of gravity, here we analyse the stability characteristics of this polymeric thin film bounded between its deformable free surface and a poorly conductive rigid substrate from below. A linear stability analysis around the quiescent base state reveals that under the combined influences of thermo-solutocapillarity, apart from the monotonic disturbance, two different oscillatory instabilities can emerge in the system. The characteristics of each instability mode are discussed, and a complete stability picture is perceived in terms of the phase diagrams, identifying the model parameter space wherein a particular instability mode can get dominant.

physics.flu-dyn↗

arXiv2012

Design and Performance Analysis of hybrid adders for high speed arithmetic circuit

Adder cells using Gate Diffusion Technique (GDI) & PTL-GDI technique are described in this paper. GDI technique allows reducing power consumption, propagation delay and low PDP (power delay product) whereas Pass Transistor Logic (PTL) reduces the count of transistors used to make different logic gates, by eliminating redundant transistors. Performance comparison with various Hybrid Adder is been presented. In this paper, we propose two new designs based on GDI & PTL techniques, which is found to be much more power efficient in comparison with existing design technique. Only 10 transistors are used to implement the SUM & CARRY function for both the designs. The SUM and CARRY cell are implemented in a cascaded way i.e. firstly the XOR cell is implemented and then using XOR as input SUM as well as CARRY cell is implemented. For Proposed GDI adder the SUM as well as CARRY cell is designed using GDI technique. On the other hand in Proposed PTL-GDI adder the SUM cell is constructed using PTL technique and the CARRY cell is designed using GDI technique. The advantages of both the designs are discussed. The significance of these designs is substantiated by the simulation results obtained from Cadence Virtuoso 180nm environment.

cs.AR↗