恒定磁场下的磁性液滴变形数值模拟

采用商业数值软件Fluent模拟研究磁液滴在恒定磁场中的运动变形情况.模拟考查磁液滴在空气中处于悬浮状态时,受到水平方向的恒磁场作用,进而发生运动变形行为.研究结果表明:磁通密度越大,对液滴造成的影响越大,液滴更加容易发生移动变形行为;另外,磁液滴尺寸越大,越容易受到磁场的影响发生变形;磁液滴发生变形存在最低磁通密度,即临界磁通密度,该参数随液滴直径的增加而减少;当液滴尺寸无限小,无论施加何种强度的磁通密度均无法实现液滴的变形;当液滴直径达到5.4 mm以上时,即便不存在磁场作用,在无外界能量维系的前提下,液滴本身也会发生变形,无法保持液滴球形的完整性.

Deformation of a Ferrofluid Droplet Under Effect of a Constant Magnetic Field: A Numerical Simulation

A commercial numerical software, FLUENT, is employed to simulate a ferrofluid droplet under the effect of a constant magnetic field, and the rules of movement and deformation of droplets are unveiled. When a ferrofluid droplet is subjected to the additional action produced by a horizontal constant magnetic field, deformation of the droplet appears. The results reveal interesting changes: (1) The larger the magnetic induction intensity, the greater the magnetic impact on a droplet, i.e., the ferrofluid droplet is tend to deform. In addition, the larger the diameter of a droplet, the easier the droplet is to deform. (2) (2) There is critical magnetic induction intensity for droplet deformation. The critical magnetic induction intensity is a minimum magnetic induction value at which a ferrofluid droplet starts to deform. The critical magnetic induction intensity decreases as the droplet diameter d increases. (3) When droplet size is infinitely small, no matter what intensity of magnetic induction is, the droplet cannot deform. When the diameter of the droplet is more than 5.4 mm, even if there is no magnetic field, the droplet itself will deform without any external energy, i.e., the spherical shape of the droplet cannot be maintained.