The supercritical modes of water convection at room temperature in an elongated horizontal cavity, with a ratio of width to height from 1:1 to 5:1 are investigated. The Prandtl number is assumed to be seven. A constant heat flux is set at the upper free and lower solid boundaries, and the side solid walls are assumed to be thermally insulated. Calculations carried out by the finite-difference method for values of the Grashof number exceeding the critical one by up to fifty times have shown that in the considered range of Grashof numbers in moderately elongated cavities, with the aspect ratios of up to 4:1, a single-vortex stationary regime is realized in the supercritical region. In a cavity with the aspect ratio of 5:1 for a wide range of Grashof numbers, a multiplicity of stationary regimes is possible, from onevortex to three-vortex. Hysteresis transitions between them, taking place at a smooth and stepwise change in the Grashof number, have been discovered and investigated.

研究了室温下水在对流中的超临界模式，其宽高比为1：1至5：1。假定普朗特数为7。在上部和下部固体边界处设置了恒定的热通量，并假定侧面固体壁是隔热的。用有限差分法计算的格拉斯霍夫数超过临界值达50倍，结果表明，在考虑的格拉斯霍夫数范围内，中等伸长的型腔的纵横比最大为4：1，在超临界区实现了单涡旋平稳态。对于宽范围的Grashof数，在长宽比为5：1的腔中，从一个涡旋到三个涡旋，可能有多种固定状态。