Alaa Abdelwahed El-Bary

This work presents a novel theoretical model for thermoacoustic wave propagation in saturated poroelastic media, incorporating hydrodynamic and thermal relaxation effects. The model integrates generalized thermoelasticity with Biot’s poroelastic theory to describe the coupled interactions among solid deformation, pore fluid pressure, temperature variation, and acoustic pressure generation. A system of coupled partial differential equations is formulated, including the equations of motion for the solid matrix, Darcy’s law for fluid flow, a generalized heat conduction equation with thermal relaxation time, and an acoustic pressure wave equation driven by thermal, mechanical, and pore pressure sources. The normal mode analysis method is applied to derive analytical expressions for the wave fields in a one-dimensional configuration. Numerical simulations are conducted to investigate the effects of porosity, permeability, thermal relaxation time, and hydrodynamic coupling on the thermoacoustic response. The results reveal that both thermal relaxation and fluid flow have a significant influence on wave speed, amplitude attenuation, and acoustic signal delay, providing enhanced physical insights into wave behavior in fluid-saturated porous materials. This study presents a comprehensive framework that can benefit applications in biomedical imaging, subsurface exploration, and the characterization of porous materials.

Purpose: This work develops a new fractional photo-thermoelastic model to investigate acoustic wave propagation in a damaged magneto-porous microelongated semiconductor medium under hydrodynamic interactions. The study focuses on clarifying the combined influence of fractional thermal memory and material damage on the coupled thermal, mechanical, carrier-density, and acoustic responses of porous semiconductors subjected to photo-thermal excitation. Design/methodology/approach: A two-dimensional mathematical formulation is established by coupling generalized thermoelasticity, poroelasticity, microelongation theory, carrier transport, and magneto-hydrodynamic interactions within a damaged semiconductor framework. A single Caputo fractional-order parameter is introduced into the heat conduction equation to characterize memory-dependent thermal diffusion, while the damage parameter is incorporated into the constitutive relations to represent material degradation and stiffness reduction. The governing equations are transformed into ordinary differential equations through the normal mode technique, and analytical solutions are obtained under suitable boundary conditions. Numerical computations are carried out for porous silicon material to evaluate the distributions of temperature, stress, acoustic pressure, carrier concentration, displacement, and microstretch fields. Findings: The obtained results demonstrate that the fractional-order parameter strongly affects the attenuation, phase delay, and propagation speed of thermoelastic and acoustic waves. Lower fractional-order values generate pronounced memory effects and smoother thermal responses, accompanied by significant reductions in stress and acoustic amplitudes. Moreover, material damage weakens the elastic resistance of the porous semiconductor and accelerates wave attenuation, particularly in the acoustic and carrier-density fields. The combined action of magnetic field, hydrodynamic interaction, and fractional thermal memory produces highly dispersive coupled wave behavior within the damaged microstructured medium. Originality/value: The novelty of this study lies in presenting a unified fractional thermoelastic acoustic model for damaged magneto-porous microelongated semiconductors with hydrodynamic effects. Unlike previous formulations, the proposed model incorporates both fractional thermal memory and damage-dependent constitutive behavior within a coupled photo-thermoelastic semiconductor framework. The developed model provides useful insights for the analysis and design of nanoscale semiconductor devices, acoustic sensing systems, porous optoelectronic structures and laser-based thermal technologies.