Prediction of boiling flow characteristics in rough and smooth microchannels using molecular dynamics simulation: Investigation the effects of boundary wall temperatures

摘要

This paper presents a molecular dynamics study on the effects of different boundary wall temperatures in the range of 84 K to 133 K on the flow characteristics of Argon fluid flow. An external force of 0.002 eV/angstrom is enforced on the fluid at the entry of microchannels with roughened and smooth surfaces. Roughness elements are in cubic shape, and fluid atoms are structured inside microchannel in two lateral regions near microchannel walls, while; middle region of the microchannel contains no fluid atom at first. Then, with the passage of computational running, Argon atoms are translocated from two symmetric lateral regions of the microchannel to empty region in the middle segment, under phase change condition. The phase change is prepared by applying different boundary walls temperatures in the order of 84 K, 96 K, 108 K,114 K, and 133 K. Then, sampling data of density for each case of wall temperatures is done at 4-time steps of 250,000, 500,000,750.000, and 1,000,000. Afterward, the velocity and temperature of Argon fluid flow are reported only at time step 1,000,000. Generally, it is concluded that the roughened surface reduces the intention of Argon atoms to move from lateral layers near the wall to central bins in the middle section of the channel as much as 3% to 5%. Furthermore, adding roughness elements on the smooth surface of microchannel can augmentate density fluctuation. Also, increasing wall temperatures empowers the boiling process, which reduces the effect of roughness. Moreover, roughness can decrease the average velocity of fluid flow values around 1% to 3%. (C) 2020 Elsevier B.V. All rights reserved.