In this study, the bifurcation phenomenon and the existence of dual asymmetry solutions of double-diffusive convection driven by an internal thermal and solutal source in a horizontal cavity have been investigated systematically. The problem is solved by the SIMPLE algorithm with the QUICK scheme in a non-uniform staggered grid system. The Rayleigh numbers, 200 ≤ Ra ≤ 10⁶, buoyancy ratios, −20 ≤ Nc ≤ 20, Soret numbers, 0 ≤ Sr ≤ 0.8, and Dufour numbers, 0 ≤ Df ≤ 0.8, are considered in this study. Different streamlines for the onset and evolution of static bifurcation are tracked. The paper aims to determine the critical Rayleigh numbers and buoyancy ratios for the onset of symmetry-breaking through bifurcation diagrams based on the vortex length. The results indicate that increasing buoyancy can destabilize the symmetric system. The strong couple diffusion effect delays the onset of bifurcation flow. A pair of asymmetric modes can be obtained under different initial conditions.

本研究系统地研究了水平腔内由内部热源和溶质源驱动的双扩散对流的分叉现象和双不对称解的存在。该问题在非均匀交错网格系统中由 SIMPLE 算法和 QUICK 方案解决。瑞利数，200 ≤  Ra  ≤ 10 ⁶，浮力比，-20 ≤ Nc ≤ 20，索雷数，0 ≤  Sr ≤ 0.8 和 Dufour 数，0 ≤ Df ≤ 0.8，在本研究中被考虑。跟踪静态分岔开始和演变的不同流线。本文旨在通过基于涡流长度的分岔图确定对称性破坏开始的临界瑞利数和浮力比。结果表明，增加浮力会使对称系统不稳定。强耦合扩散效应延迟了分叉流的开始。在不同的初始条件下可以获得一对非对称模式。