By means of extensive two-dimensional Direct Numerical Simulations [1,2], we investigate the settling process of a mixed fluid-particles material in a rectangular domain with a periodic condition in its x-direction. In estuarine environments, for example, we identify multiples particle sizes and densities under different forcing conditions. First, we aim to quantify the terminal settling velocity of a single particle over a broad range of geometrical parameters such as particle size and periodic domain width, as well as physical properties such as density ratio and fluid viscosity under equilibrium conditions. We show that the terminal settling velocity increases as a power law, up to a characteristic threshold beyond which no further influence of particle size is observed on the settling velocity [3]. More interestingly, the characteristic separation distance is found to obey to a power low in a phase diagram linking the fluid pressure difference and the particle settling velocity. We show that the pressure difference is related to the particle buoyant weight and it’s found to evolve inversely proportional to the separation distance. In the same way, we show that the characteristic separation distance increase while the particle Reynolds number decreases. The direct relationship between settling velocity-pressure-separation distance is found to be in the confining effect through the separation distance that governs the fluid flow behaviour surrounding the particle. In contrast to a single particle, reducing the separation distance for a multi-particle settling process, in other words increasing the packing fraction of the settling suspension, we observe an increasing of the settling velocity [4]. Settling behaviour become more complex due to particle collisions and hydrodynamics clustering. In this study, we analyze the physical behaviour of wakes, their relationship with the packing fraction and their influence on the average settling velocity compared to the case of a single particle.