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arXiv 2111.09693physics.flu-dyn
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壁面滑移的活化能

The Activation Energy for Wall Slip

Peter F. Pelz, Tobias Corneli

摘要:

Navier滑移边界条件被解释为剪切速率和滑移速率的平衡。从滑移率与分子碰撞率成正比的观点出发,导出了Navier滑移边界条件的温度依赖性。滑移长度的温度依赖性的模型进行了验证的滑移测量液态烃在一种新型的库埃特型摩擦磨损试验机正在介绍。所得的流固界面实验数据的实质是在某一参考温度下的剪切和壁面滑移的四重活化能以及粘度和滑移长度。这四个不同的烃类液体的不同分子量,结构和极性证明了新的测量方法的适用性。通过对滑移长度的系统测量,得出了滑移长度随分子量增加而增加的三个结论:(1)滑移长度随分子量的增加而增加;(2)分子结构由饱和烃向不饱和烃的变化影响滑移长度和滑移活化能;(iii)向烃中加入一小部分极性分子减少了滑移长度,并增加了由于极性末端引起的壁滑移的活化能,液体的群体。

英文摘要:

The Navier slip boundary condition is interpreted as an equilibrium of shear rate and slip rate. From the argument that the slip rate shall be proportional to the molecules' collision rate, the temperature dependence of the Navier slip boundary condition is derived. The model for the temperature dependence of the slip length is validated by slip measurements of liquid hydrocarbons in a novel Couette typ tribometer being introduced. The essence of the gained experimental data for one fluid-solid-interface is the quadruple activation energy for shear and wall slip together with the viscosity and slip length at a reference temperature. This quadruple is determined for four different hydrocarbon liquids of different molecular mass, structure and polarity proving the applicability of the new measurement method. From the executed systematic measurements three conclusions regarding the slip length dependence are pointed out: (i) the slip length increases with increasing molar mass; (ii) changing the molecular structure from saturated hydrocarbon to unsaturated affects the slip length as well as the activation energy for slip; (iii) adding a small fraction of polar molecules to the hydrocarbon decreases the slip length and increases the activation energy for wall slip due to the polar end-groups of the liquid.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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