We present a series of two-dimensional (2D) numerical simulations on thermal convection in a square and an octagonal enclosure, with heated bottom and cooled top surfaces for the range of Rayleigh number (Ra), 5 105 to 108, and the Prandtl number (Pr), 0:8 and 2. The octagon is constructed in such a way that it always inscribed in a square, with a xed horizontal length and varying slant lengths by varying the inclination angle (from 0o to 45o, where, 0o indicates square and 45o indicates regular octagonal enclosure. We nd that ariation signicantly act the ow patterns and heat transport. The ow patterns are classied into seven ow regimes, namely (1) uniform circulation (UC), (2) uniform circulation with reversal (UCR), (3) two-roll state (TRS), (4) two-roll state with reversal (TRSR), (5) periodic reversal (PR), (6) quasi-periodic reversal (QPR), and (7) mixed state with reversal (MSR) for the considered range of Ra and Pr. Further, we analyze the ow reversals by using the Fourier d ..

中文翻译：

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八角形外壳中的热对流

（7）在考虑的Ra和Pr范围内，具有反转的混合状态（MSR）。此外，我们通过使用傅立叶d ..来分析流动逆转。