Instabilities in three-dimensional boundary-layer flows with a highly non-ideal fluid

The present work investigates the linear instability of three-dimensional boundary layers in thermodynamically non-ideal regimes. As a representative fluid, we consider carbon dioxide at supercritical pressure (80 bar). flow set-up is matched to redesigned DLR (German Aerospace Center) experiment on cross-flow instability, with identical pressure-coefficient distribution (accelerating flow), sweep angle and Reynolds number, low Mach number. temperature relative Widom line – also known as pseudocritical thus characterises non-ideality flow. We (gas-like), subcritical (liquid-like) transcritical (pseudoboiling) regimes, where remains above, below or crosses line. stability analyses parabolised Navier–Stokes baseflows indicate that wall heating destabilises regime while cooling stabilises both effects similar ideal-fluid situation but being stronger. On contrary, heating/cooling exhibits reversed regime, like for an ideal liquid. In its sharp gradients thermodynamic transport properties, Most substantially, however, provokes changeover leading mechanism: accelerated streamwise attains inflectional wall-normal profiles, invoked inviscid Tollmien–Schlichting prevails growth rates up one order magnitude larger than those mode. establish two-fold mathematical relation from momentum equation explains consequence heating/cooling. perturbation patterns flows their are shown by mimicking wave trains emanating virtual point-disturbance sources. From viewpoint keeping laminar flows, state must be avoided.