An exactly force-balanced boundary-conforming arbitrary-Lagrangian-Eulerian method for interfacial dynamics

•Proof of the existence of static numerical solutions with circular interface.•Thorough study of spurious current.•Bubble/drop oscillations against analytical solutions.•Simulations of a dripping faucet with real physical parameters.•A simple, robust and automatic algorithm for handling interface breakup. We present an interface conforming method for simulating two-dimensional and axisymmetric multiphase flows. In the proposed method, the interface is composed of straight segments which are part of mesh and move with the flow. This interface representation is an integral part of an Arbitrary Lagrangian-Eulerian (ALE) method on an moving adaptive unstructured mesh. Our principal aim is to develop an accurate and robust computational method for interfacial flows driven by strong surface tension and with weak viscous dissipation. We first construct discrete solutions satisfying the Laplace law on a circular/spherical interfaces exactly, i.e., the balance between the surface tension and the pressure jump across an interface is achieved exactly in a discrete form. The accuracy and stability of these solutions are then investigated for a wide range of Ohnesorge numbers, Oh. The dimensionless amplitude of the spurious current is reduced to machine zero, i.e., on the order of 10−15 for Oh≥10−3. Finally, the accuracy and capability of the proposed method are demonstrated through a series of benchmark tests with larger interface deformations. In particular, the method is validated with Prosperitti's analytic results of the bubble/drop oscillations and Peregrine's dripping faucet experiment, in which the values of Oh are small.