A numerical investigation of an engine oil droplet normally impinging onto oil pan within crankcase of an IC engine

• We researched an oil droplet impinging onto oil pan of internal combustion engine.
• We used VOF coupled with tree-based adaptive local mesh refinement technology.
• We simulated droplet coalescence, droplet marginal splashing and droplet splashing.
• We got the time evolution of the crown formation and the surface wave.
• We compared the mesh refinement level on simulation results.

In this paper, the VOF method coupled with tree-based adaptive local mesh refinement technology is used for numerical simulation of an oil droplet normally impinging onto oil surface within crankcase of an internal combustion engine to provide evidence for the research of engine oil character. Three cases with different We numbers and Re number are considered to simulate the process of droplet coalescence, droplet marginal splashing and droplet splashing. For all cases, at time around t = 0 ms, the velocity and pressure rises to a peak between droplet and liquid surface, and then decreased to a quasi-stable value. The dimensionless center height shows an approximate same trend for each case: firstly decreases sharply and then shows a logarithmic growth. As time goes on, the center height curve will approach zero with the impinging energy dissipating. The dimensionless maximum height can be divided into three parts with three peaks: (a) the crown crest; (b) the crown spreading on the wall; (c) the center rebounding liquid. The dimensionless crown radius shows a similar hyperbolic-type shape. A case with higher local mesh refinement levels shows more accurate phase interface which costs more computational time and storage.