A Modeling of Toms Effect Based on the Discrete Element Model

基于离散元模型的Toms效应建模

• 批准号: 16560169
• 负责人: KURODA Akiyoshi
• 金额: $ 1.98万
• 依托单位: HOKKAIDO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16560169/
• 关键词: turbulent flow; Toms effect; drag reduction; modeling; numerical simulation; non-Newtonian fluid

A model to simulate the drag reductoin by dilute addition of polymer or surfactant (Toms effect) is proposed based on the discrete element model. The dimension of the discrete element, which represents the polymer or the rod-like micelle, is very small compared to that of the velocity fluctuation of the fluid. So it is assumed that the element is in equilibrium state in the fluid and turns to the direction of an eigenvector of the velocity gradient tensor. And the macroscopic effect of the discrete elements is modeled as the stress assuming the elements are independent each other. Direct numerical simulations are carried out with this new model using the rigid dumbbell element as a discrete element model and it is shown that the drag reduction up to 37% drag reduction rate is reproduced. In addition the followings are indicated as concluding remarks. (1)The drag reduction can be reproduced without assuming the macrostructures formed as the network of elongated polymers or rod-like micelles. (2)The drag reduction and the stress deficit can be reproduced without the elasticity.In addition study, new character is added on the model, say, the dumbbell element which simulate a polymer can be cut by the stretching force in the fluid. Simulations of 2D channel flows (Re_τ=120-600) are carried out and the drag reduction up to 50% drag reduction rate is reproduced by the modified model.

在离散元模型的基础上，提出了一种模拟聚合物或表面活性剂稀加减阻(TOMS效应)的模型。与流体的速度脉动相比，代表聚合物或棒状胶束的离散单元的尺寸很小。因此，假设单元在流体中处于平衡状态，并转向速度梯度张量的特征向量的方向。在单元相互独立的情况下，将离散单元的宏观效应模拟为应力。采用刚性哑铃单元作为离散单元，对该模型进行了直接数值模拟，结果表明，该模型的减阻率可达37%。此外，以下为结束语。(1)可以复制减阻，而无需假设宏观结构形成为细长聚合物或棒状胶束的网络。(2)可以在没有弹性的情况下再现减阻和应力亏损，此外，研究还增加了新的特性，即模拟聚合物的哑铃单元可以被流体中的拉力切割。对二维槽道流动(Re_τ=12 0~6 0 0)进行了数值模拟，得到了高达5 0%的减阻率。

项目成果

離散要素の概念に基づくトムズ効果のモデリング

基于离散元素概念的汤姆斯效应建模

• 发表时间: 2004
• 期刊: 日本機械学会論文集(B編) 70巻・698号
• 作者: B.B.Saha;S.Koyama;I.I.El-Sharkawy;K.Kuwahara;K.Kariya;J.B.Lee;黒田明慈
• 通讯作者: 黒田明慈

A Modelling of Toms Effect Based on the Discrete Element Model

基于离散元模型的Toms效应建模

• 发表时间: 2004
• 期刊: Trans.JSME (B) (in Japanese) 70-698
• 作者: Akiyoshi KURODA;Kazuhiko KUDO
• 通讯作者: Kazuhiko KUDO

On the Mechanism of Drag Reduction by Toms Effect

汤姆斯效应减阻机理探讨

• 发表时间: 2004
• 期刊: Thermal Science and Engineering 12-4
• 作者: B.B.Saha;S.Koyama;I.I.El-Sharkawy;K.Kuwahara;K.Kariya;J.B.Lee;黒田明慈;Akiyoshi KURODA
• 通讯作者: Akiyoshi KURODA