Comp. Part. Mech. DOI 10.1007/s40571-017-0157-4 A mesoscopic simulation of static and dynamic wetting using many-body dissipative particle dynamics Najmeh Ghorbani 1 · Ahmadreza Pishevar 1 Received: 27 September 2016 / Revised: 28 February 2017 / Accepted: 14 March 2017 © OWZ 2017 Abstract A many-body dissipative particle dynamics sim- ulation is applied here to pave the way for investigating the behavior of mesoscale droplets after impact on hori- zontal solid substrates. First, hydrophobic and hydrophilic substrates are simulated through tuning the solid–liquid inter- facial interaction parameters of an innovative conservative force model. The static contact angles are calculated on homogeneous and several patterned surfaces and compared with the predicted values by the Cassie’s law in order to ver- ify the model. The results properly evaluate the amount of increase in surface superhydrophobicity as a result of surface patterning. Then drop impact phenomenon is studied by cal- culating the spreading factor and dimensionless height versus dimensionless time and the comparisons made between the results and the experimental values for three different static contact angles. The results show the capability of the proce- dure in calculating the amount of maximum spreading factor, which is a significant concept in ink-jet printing and coating process. Keywords Many-body dissipative particle dynamics · Wettability · Patterned substrate · Static contact angle · Drop impact · Spreading factor 1 Introduction The behavior of liquid on solid substrates is an impor- tant phenomenon in fuel injection systems, ink-jet printing [1–4], DNA microarrays [5], spray cooling and many others B Ahmadreza Pishevar apishe@cc.iut.ac.ir 1 Department of Mechanical Engineering, Isfahan University of Technology, Isfahan 8415683111, Iran in chemical processes. The complexity of the various intrinsic properties such as capillarity, surface topology and non- Newtonian character of the liquid makes the understanding of this behavior as a scientific challenge. In this regard, some studies have focused on dominant dimensionless numbers [6], and some others have reported drop spreading depen- dency on wettability [7] to study this phenomenon. In this paper, both dominant dimensionless numbers and wettability are our main concern. One of these dimensionless numbers is Reynolds number ( Re = ρ DV /μ), where ρ is the den- sity of the fluid, D is the initial diameter of the droplet, V is the drop impact velocity and μ is the viscosity of the fluid. This number remains between 1 and 100 for many ink-jet operations because of the small diameter of the nozzle even at high jetting velocity. But in many of the experiments that have been performed to study the drop spreading so far, Re is between 100 and 2000 with initial droplet diameter of 2–3 mm [8]. This experimental limitation, as with many oth- ers, e.g., gravity, liquid sorption, evaporation and penetration effects, and also lack of a comprehensive analytical model for studying the behavior of mesoscale liquid drops on various solid surfaces persuade us to apply numerical simulations for this purpose. In this regard, some methods such as molecular dynamics (MD) and Monte Carlo have been used to ana- lyze the behavior of a drop on solid surface. However, these methods are limited to small time (∼1 ns) and length scales (∼1nm). To study this phenomenon when length and time scales rise to a mesoscopic level, a coarse-grained method is required to reduce the computational cost [9]. Among dif- ferent mesoscale methods proposed so far, a particle-based method called many-body dissipative particle dynamics [10] has received special attention due to its intrinsic property of interface capturing. In MDPD, each particle contains a collection of atoms or molecules which only interacts with particles that are within its certain cutoff distance. Contrary to 123