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Time-periodic thermal boundary effects on porous media saturated with nanofluids : CGLE model for oscillatory mode

Kiran Palle, Manjula Sivaraj H.

Advances in Materials Science

2022

Vol. 22, nr 4(74)

98--116

The stability of nonlinear nanofluid convection is examined using the complex matrix differential operator theory. With the help of finite amplitude analysis, nonlinear convection in a porous medium is investigated that has been saturated with nanofluid and subjected to thermal modulation. The complex Ginzburg-Landau equation (CGLE) is used to determine the finite amplitude convection in order to evaluate heat and mass transfer. The small amplitude of convection is considered to determine heat and mass transfer through the porous medium. Thermal modulation of the system is predicted to change sinusoidally over time, as shown at the boundary. Three distinct modulations IPM, OPM, and LBMOhave been investigated and found that OPM and LBMO cases are used to regulate heat and mass transfer. Further, it is found that modulation frequency (ωf varying from 2 to 70) reduces heat and mass transfer while modulation amplitude (δ1varying from 0.1 to 0.5 ) enhances both.

The effect of modulation on heat transport by a weakly nonlinear thermal instability in the presence of applied magnetic field and internal heating

Manjula S. H., Kiran Palle, Narsimlu G., Roslan R.

International Journal of Applied Mechanics and Engineering

2020

Vol. 25, no. 4

96--115

The present paper deals with a weakly nonlinear stability problem under an imposed time-periodic thermal modulation. The temperature has two parts: a constant part and an externally imposed time-dependent part. We focus on stationary convection using the slow time scale and quantify convective amplitude through the real Ginzburg-Landau equation (GLE). We have used the classical fourth order Runge-Kutta method to solve the real Ginzburg-Landau equation. The effect of various parameters on heat transport is discussed through GLE. It is found that heat transport analysis is controlled by suitably adjusting the frequency and amplitude of modulation. The applied magnetic field (effect of Ha) is to diminish the heat transfer in the system. Three different types of modulations thermal, gravity, and magnetic field have been compared. It is concluded that thermal modulation is more effective than gravity and magnetic modulation. The magnetic modulation stabilizes more and gravity modulation stabilizes partially than thermal modulation.