Hamidreza Eivazi

Sep 19, 2024 | pubs.aip.org | De Montfort |Crystal Owens |Zengshun Chen |Hamidreza Eivazi

In the current study, the anti-gravity directional self-migration of droplets on an inclined surface driven by wettability gradient (⁠ ⁠) was investigated using a front-tracking method. A unified mechanical model of droplet motion on an inclined wettability gradient wall was derived, considering the driving force generated by (⁠ ⁠), gravity (⁠ ⁠), and flow resistance (⁠ ⁠). The model demonstrates that ⁠, ⁠, and inclination angle (⁠ ⁠) are key parameters affecting droplet motion.

Sep 17, 2024 | pubs.aip.org | Crystal Owens |Zengshun Chen |Hamidreza Eivazi

Semi-local scales have been widely used in compressible wall-bounded turbulence, but it is still unclear whether they are applicable to the scaling of coherent structures, especially under conditions of high Mach number and cold wall temperature. By scrutinizing the direct numerical simulation dataset at different Mach numbers and wall temperatures, this paper demonstrates that the coherent structures normalized by semi-local scales are universal in size.

Sep 16, 2024 | pubs.aip.org | Crystal Owens |Zengshun Chen |Hamidreza Eivazi

Film cooling plays a critical role in protecting engine components from high temperatures that can influence safety and performance of gas turbines. However, the process is fraught with uncertainties due to complex inflow conditions and geometrical configurations. These uncertainties significantly impact cooling effectiveness, underscoring the importance of identifying the dominant factors in a quantified manner.

Sep 10, 2024 | pubs.aip.org | Crystal Owens |Zengshun Chen |Hamidreza Eivazi

During atmospheric reentry, the vehicle surface is exposed to highly non-equilibrium flow. The vehicle surface can experience heterogeneous recombination of reactive atoms, which contributes to its aerothermodynamic heating. This process is followed by chemical energy accommodation (CEA), where the released energy is either transferred to the surface or the internal energy modes of the recombined molecule.

Jul 26, 2024 | pubs.aip.org | Zengshun Chen |Crystal Owens |Hamidreza Eivazi

A component-splitting method is proposed to improve the convergence characteristics of the implicit time integration for compressible multicomponent reactive flows. The characteristic decomposition of the flux Jacobian in multicomponent Navier–Stokes equations yields a large sparse eigensystem, presenting challenges of slow convergence and high computational cost for the implicit methods.