The effect of aiding and opposing buoyancy (−1 ≤ Ri ≤ 1) on flow and heat transfer across cylinders specifically arranged in an equilateral triangular array in a heat exchanger has not previously been studied. Periodic boundary condition in the transverse direction is imposed where porosity of the array ranges from 0.7 to 0.99. The influence of buoyancy and Prandtl number (1 and 50) on the flow structure and its effect on the overall heat transfer is thoroughly elucidated in the present work. The impact of aiding/opposing buoyancy on the thermal performance of the array is predominant at higher porosities. The average drag of the array of cylinders increases with an increase in the aiding buoyancy and decreases with an increase in opposing buoyancy with respect to forced convection. The porosity of the triangular array has an inverse relation with the average drag coefficient, barring few exceptions which are explained in detail in the present work. The heat exchange is assertively higher at opposing‐buoyancy cases for all values of porosity and Prandtl number. The present results are in agreement with the available experimental/numerical studies.

中文翻译：

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混合对流通过周期性加热/冷却气缸的各向同性多孔三角形阵列对流动动力学和传热的影响

以前尚未研究过辅助浮力（-1≤Ri≤1）对反向流动的影响，这种流动对跨过专门布置在热交换器中等边三角形阵列中的圆柱体的流动和传热的影响。施加横向的周期性边界条件，其中阵列的孔隙率在0.7至0.99的范围内。浮力和普朗特数（1和50）对流动结构的影响及其对整体传热的影响在本工作中已得到充分阐明。在较高的孔隙率下，辅助/相反的浮力对阵列的热性能的影响尤为明显。相对于强制对流，圆柱阵列的平均阻力随着辅助浮力的增加而增加，而随着反向浮力的增加而减小。三角形阵列的孔隙率与平均阻力系数成反比，除非有例外，否则将在本工作中详细说明。对于所有孔隙度和普朗特数的反浮力情况，热交换都肯定更高。目前的结果与可用的实验/数值研究一致。