2025/02/13 by V. K. Tripathi, Pranav Joshi, Tripathi, V. K. +1
Biochemistry, Genetics and Molecular Biology · #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Geomagnetism and Paleomagnetism Studies
paper · pdf · doi:10.48550/arxiv.2502.09174
openalex publication_date 2025/02/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We perform direct numerical simulations (DNS) to study the effect of bi-lateral confinement, i.e., the effect of aspect ratio, on the Rayleigh number (Ra) for the onset of wall-mode convection (Rawm) in rotating Rayleigh-Bénard convection (RBC) for various Ekman number E (10-2≤E≤10-5) and aspect ratio Γ (0.08≤Γ≤5). For a given E, as the aspect ratio is lowered from a large value, Rawm initially decreases slowly, reaching a minimum at Γ=Γmin (Γmin∼E0.09). As Γ is decreased further below Γmin, Rawm increases rapidly and for sufficiently strong confinement, i.e., Γ<Γ∗ (Γ∗∼E(1)/(3)), becomes indistinguishable from Rac, the critical Rayleigh number for non-rotating RBC, at the same Γ. We designate the ranges Γmin<Γ<5 as the 'confinement-affected' regime and Γ<Γ∗ as the 'spatially constrained' regime. For a given rotation rate, the spatially constrained regime extends to higher Ra as the aspect ratio is decreased. We propose that in this regime, strong lateral confinement suppresses the horizontal velocity, and hence the Coriolis force, rendering rotation ineffective over most of the domain.