【摘要】 为了研究微纳尺度下流体密度、壁面剪切速度以及不同材料的壁面对流体流动特性的影响,采用分子动力学方法对流体在微纳尺度下的Couette流动进行模拟。研究结果表明:随着流体密度增加流体与壁面作用力增大,壁面对近壁流体的束缚也增强,近壁面处流体粒子自由运动减弱导致流体扩散能力下降,同时流体等效黏度随密度增加而增大,滑移量减小;壁面剪切速度增大,导致近壁面处流体粒子数减少,流体等效黏度降低,流体粒子在通道中更容易进行无规则自由运动使其扩散能力增强;通过改变壁面材料,发现金属壁面作用力强于非金属,在金属材料近壁面处更容易吸附较多流体粒子,导致金属壁面附近流体等效黏度较大,滑移量相对较小。更多还原

【Abstract】 The dynamics of Couette flow at micro-nano scale was simulated by molecular dynamics method. The influence of fluid density,wall shear velocity and properties of different wall materials on fluid Couette flow characteristics were analyzed. The results show that the interaction of forces between wall and fluid on near wall increases,and restraint of the wall surface to fluid on the near-wall was enhanced with increasing of fluid density. The fluid diffusion property decreases yet fluid equivalent viscosity increases,the slippage decreases due to the movement weakening of the fluid at the near wall surface. When the wall shearing velocity increases,the fluid density decreases near the wall surface and the fluid equivalent viscosity decreases,the fluid molecules are more likely to perform random free motion,and the diffusion property was enhanced in the micro-nano scale channel. When the wall material is changed,it is found that the interaction on metal wall surface is stronger than that of non-metal surface,and more fluid molecule are easily adsorbed at the near wall surface of the metal material,which is resulted in a larger fluid equivalent viscosity near the metal wall surface and a relatively small slip amount.更多还原