Onset of convection in binary gas mixtures: Role of the Dufour effect

Abstract

The stability behavior of the conductive state of binary gas mixtures in the Rayleigh-Benard setup is significantly altered in comparison to binary liquid mixtures due to their different thermodynamic and transport properties. In particular, the Dufour effect influences dramatically the topology and the existence ranges of the oscillatory and stationary instabilities for Dufour and Lewis numbers that are typical in gas mixtures. We present a detailed investigation of the changes of the stability properties for several types of boundary conditions including the realistic no-slip, impermeable ones.

Convective Patterns in Binary Fluid Mixtures with Positive Separation Ratios

“…The Dufour effect, i.e., the driving of temperature currents by concentration variations is of interest only in gas mixtures [9]. But even there it is often small [10].…”

“…Here ̺ 0 is the mean density, D th the thermal diffusivity, ν the kinematic viscosity, and α = −(1/ρ)∂ρ/∂T and β = −(1/ρ)∂ρ/∂C are thermal and solutal expansion coefficients, respectively. Using the Oberbeck-Boussinesq approximation the balance equations read [2,9] ∇ · u = 0 (4a)…”

Traveling wave fronts and localized traveling wave convection in binary fluid mixtures

“…The Dufour effect [53,54] that provides a coupling of concentration gradients into the heat current and a change of the thermal diffusivity is discarded in (1.1c) since it is relevant only in few binary gas mixtures [55] and possibly in liquids near the liquid-vapor critical point [56].…”

Oscillatory convection in binary mixtures: Thermodiffusion, solutal buoyancy, and advection

“…B is the buoyancy. The Dufour effect [20,21] that provides a coupling of concentration gradients into the heat current Q and a change of the thermal diffusivity is discarded in (2.3) since it is relevant only in few binary gas mixtures [22] and possibly in liquids near the liquid-vapor critical point [23].…”