基于晶格Boltzmann方法研究微液滴形变中接触角

Contact Angle in Micro Droplet Deformation Based on Lattice Boltzmann Method

接触角是常见的自然现象,是液体对固体表面浸润的结果,通过测量接触角可以判断固体表面亲疏液体的性质。从热力学自由能理论出发,采用基于化学势的多相流晶格Boltzmann方法研究表面上微小液滴形变中的接触角变化。通过设置不同的化学势来改变固体表面的亲疏液体性质,模拟计算中既有落在固体表面之上的液滴,也包括悬挂在固体表面下方的液滴。在忽略重力作用的情况下,模拟得到的接触角与球冠法的理论预期一致,并且液滴的接触角可以通过表面化学势线性调节。在考虑重力作用的情况下,虽然不同大小的液滴发生了明显的不同程度的形变,但是模拟计算所得的接触角保持不变,验证了微观接触角与重力无关的理论。

Contact angle is a common natural phenomenon,which is the result of liquid wetting on the solid surface.The surface wettability can be examined by measuring the contact angle.Starting from the free energy principle,the multi-phase Lattice Boltzmann method based on chemical potential is used to study the contact angle in the deformation of tiny droplets on the surface.The hydrophilic and hydrophobic properties of the solid surface can be changed by setting different chemical potential.The present simulations include both the sessile droplets standing on the surface and the pendent droplets adsorbing below the surface.Ignoring the effect of gravity,the simulating contact angle is consistent to the theoretical results of the spherical crown method,and the contact angle can be linearly adjusted by the surface chemical potential.Considering the effect of gravity,although the droplets of different sizes have some degrees of obvious deformations,the contact angle computed by the present method remains the same;this verifies the theoretical analysis that the microscopic contact angle is independent of the gravity.