arXiv subjects

Adrián Antón-Álvarez

Publications and source records attributed to Adrián Antón-Álvarez.

3 recordsLinked to original sources

arXiv2026

Global modal/non-modal analysis of high-enthalpy Martian entry vehicles

We analyze laminar-to-turbulent transition over a blunt capsule representative of Martian entry at Mach 26 using global modal and transient-growth analyses about a thermochemical base flow characteristic of high-altitude entry conditions. Across the Reynolds-number range considered ($Re_\infty = 10^4$--$10^6$), the axisymmetric global eigenspectrum remains stable, ruling out temporally unstable axisymmetric global modes as a viable route to transition. The flow nevertheless supports strong transient growth concentrated in the shear--entropy layer generated by bow-shock curvature. Energy-budget analysis reveals a two-stage process: Reynolds-stress production in the mean shear first amplifies kinetic disturbances, which then generate entropy fluctuations as they traverse the strong base-flow entropy gradient. The optimal gain scales linearly with the Reynolds number based on the capsule nose radius, whereas boundary-layer-localized disturbances become competitive at the highest Reynolds numbers examined. These results identify shear--entropy-layer transient growth as a plausible linear pathway for seeding transition in high-enthalpy blunt-entry vehicles.

physics.flu-dyn↗

arXiv2026

HYMOR: An open-source package for global modal, non-modal, and receptivity analysis in high-enthalpy hypersonic vehicles

We present HYMOR (HYpersonic MOdal/non-modal, and Receptivity), an open-source computational framework for the linear stability analysis of high-enthalpy hypersonic flows. The toolkit includes MATLAB and Julia implementations and is released under the MIT license. HYMOR provides global modal, non-modal, and freestream receptivity analyses capable of capturing interactions among spatially separated physical mechanisms that are inaccessible to traditional local methods. A shock-fitting formulation is employed to treat the bow shock as a sharp discontinuity, ensuring that the interaction of infinitesimal disturbances with the shock reproduces the exact response predicted by linear interaction analysis. The code also solves the nonlinear equations for base-flow computation and automatically linearizes the resulting discrete operators for the stability analyses. Several thermochemical models are available for treatment of real-gas effects in high-enthalpy regimes. The numerical implementation is verified against a collection of benchmark cases that demonstrate the accuracy and capabilities of the toolkit across its modal, non-modal, and receptivity analysis modes.

physics.flu-dyn↗

arXiv2026

Bow-shock instability in entry, descent, and landing vehicles under high-enthalpy conditions

Laminar--turbulent transition remains a major uncertainty in the aerothermal design of entry, descent, and landing (EDL) vehicles. We show that, under high-enthalpy Mars-entry conditions, the detached bow shock and shock-generated shear--entropy layer can become unstable under freestream disturbances, leading to nonlinear breakdown and enhanced wall heating. The analysis spans freestream Mach numbers ($M_\infty$) up to 30 for both Earth and Mars at high altitude, with Mars being more susceptible. The receptivity analysis shows that disturbance amplification occurs through a three-step mechanism: (i) transmission and amplification of acoustic and entropic freestream components across the bow shock; (ii) further convective amplification within the post-shock shear--entropy layer; and (iii) bow-shock corrugation driven by the downstream pressure field, which reinforces the instability. The dominant response is localized in the shock layer, with no classical boundary-layer mode required. The total optimal energy gain scales as $\overline{G}_T^{\rm opt}\sim γ_2^*M_\infty^2 \exp[(ρ_2/ρ_1)/C-B/\sqrt{Re_\infty}]$, where $γ_2^*$ is an effective specific-heat ratio, $ρ_1$ and $ρ_2$ the pre- and post-shock densities, $Re_\infty$ the freestream Reynolds number, and $B$, $C$ geometry-dependent constants. For a representative EDL vehicle during Mars entry, amplification factors reach order $10^6$. Flight measurements from the Mars Science Laboratory (MSL) and Mars 2020/Perseverance capsules are consistent with these results, as are wall-modeled large-eddy simulations of MSL under representative Mars-entry conditions. These results suggest that bow-shock instabilities may constitute a transition mechanism for blunt hypersonic entry vehicles, either alone or combined with others.

physics.flu-dyn↗