TY - JOUR A1 - Bierler, Jonas A1 - Matioc, Bogdan-Vasile PB - EUROPEAN MATHEMATICAL SOC-EMS SN - 1463-9963 SN - 1463-9971 EP - 196 ID - epub56955 KW - WELL-POSEDNESS; SPLASH SINGULARITIES; POROUS-MEDIA; 3-PHASE FLOW; HELE-SHAW; INTERFACE; REGULARITY; EXISTENCE; FLUIDS; Multiphase Muskat problem; parabolic evolution equation; singular integral; subcritical spaces JF - Interfaces and Free Boundaries AV - none SP - 163 TI - The multiphase Muskat problem with equal viscosities in two dimensions VL - 24 N2 - We study the two-dimensional multiphase Muskat problem describing the motion of three immiscible fluids with equal viscosities in a vertical homogeneous porous medium identified with R2 under the effect of gravity. We first formulate the governing equations as a strongly coupled evolution problem for the functions that parameterize the sharp interfaces between the fluids. Afterwards we prove that the problem is of parabolic type and establish its well-posedness together with two parabolic smoothing properties. For solutions that are not global we exclude, in a certain regime, that the interfaces come into contact along a curve segment. IS - 2 UR - http://doi.org/10.4171/IFB/469 CY - BERLIN Y1 - 2021/// ER -