Liquid–solid fluidized beds (LSFBs) find several industrial applications, where a clear understanding of bed expansion demeanor, phase distribution, solid segregation and intermixing is inevitable. Here, a transient multi-Eulerian model with granular flow extension is presented to investigate the segregation characteristics in a polydisperse LSFB. Both segregated and intermixed zones were encountered in the expanded bed based on variability in particle diameters and densities. The influences of liquid superficial velocity, viscosity and density on particle segregation are elaborated. For the considered system, liquid density was found to render more discerning influence on particle segregation.