The manipulation of ferrofluidic droplets by magnetic fields is a popular technique for controlling fluid transport in open microfluidic systems. We examine the effect of gravity and shear flow external forces on the adhesion properties of sessile ferrofluidic droplets in the presence of a uniform magnetic field. The magnetic field was found to enhance the critical Bond number at which sliding begins on a tilting substrate but suppress the critical Weber number at which sliding begins in a moderate Reynolds number channel flow. The divergent adhesion trends are explained in terms of the shape deformation induced in the ferrofluidic droplet, the substrate wettability, and the apparent contact angle variation induced by the droplet deformation.

中文翻译：

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剪切流中和倾斜表面上铁磁流体液滴粘附的磁控制。

磁场对铁磁流体液滴的控制是一种用于控制开放微流体系统中流体传输的流行技术。我们研究了在均匀磁场存在下，重力和剪切流外力对固着铁磁流体液滴粘附性能的影响。发现磁场增强了在倾斜基板上开始滑动的临界键数，但抑制了中等雷诺数通道流动中开始滑动的临界韦伯数。根据在铁磁流体小滴中引起的形状变形，基材润湿性以及由小滴变形引起的表观接触角变化来解释不同的粘附趋势。