discrete element method

A cylindrical sieve, characterized by its simple structure, lightweight, negligible vibration, and lower energy consumption compared to other separation systems used in combines. This type of screen can serve as an alternative cleaning system for rice-threshed mixture when combined with air flow. This research employed computational fluid dynamics (CFD) and the discrete element method (DEM) to explore and enhance the understanding of the operational parameters influencing the performance of the cleaning sieve. The study examined the impact of air flow velocity and the rotational speed of the sieve on various separation indices, such as the cleanliness ratio, loss ratio, and efficiency. Findings indicated that air flow velocity significantly influences the average axial speed of the mixture components. The rotational speed of the sieve has a significant effect on both the loss ratio and the sieve's efficiency. In this study, Rocky DEM software was utilized as an alternative to EDEM for simulating the discrete flow of granular materials. The results of this study were validated through comparisons with earlier research that utilized EDEM software for simulations. Rocky DEM software developed by the provider of ANSYS Fluent, Rocky DEM enables the simulation of interactions between discrete particles and fluid flow using the coupled CFD-DEM method. Consequently, it serves as a viable replacement for EDEM, which has been extensively applied in agricultural research and engineering.

Discrete element method has been identified as a suitable method for studying the flow of granular materials. In this research, the motion of Persian lilac fruit was initially investigated experimentally in a slopped hopper and then it was simulated using discrete element method. The experiments were carried out on the basis of factorial design with two factors of height and discharge area, each at four levels. The ANOVA tests indicated that the height of the fruits in the hopper and the surface area of the discharge and their interaction had a significant effect on the outflow of the fruits. The developed regression equation between the mass flow rate and discharge area and the interaction of discharge area and height was linear (R2 = 0.99), however, height of the fruits in the hopper had a negative impact on the discharge rate. The simulation results indicated that and the outlet size, the discharge flow and the output velocity increase, but they did not exactly follow the fluid flow relationships. The effect of fruits friction showed that the discharge rate increased with decreasing internal friction. In general, comparing the simulation results with laboratory tests showed that the discrete element method was well able to simulate the flow of particles within and through the hopper.

Interaction between soil and machine is essential challenge for researchers, developers, designers and manufacturers of agricultural machineries. Modeling of tillage equipment is an important Engineering work. However, interaction modeling is a complex process due to three-dimensional changes in soil, nonlinear soil behavior phenomenon and soil flow quality in connection area between the soil and tool and the dynamic effects of equipment. Correct simulation of the interaction of soil is the key point for the optimization of tillage tools and can eliminate required field tests with high costs. The purpose of this study is to develop a three-dimensional model of a vibrating subsoiler using discrete element method, simulation frequency and oscillation angle on the performance of vibration subsoiler and determining different parameters affecting the simulation results. The information from model simulation will be useful for the design and optimization of vibrating subsoiler. For modeling soil mass as a granular material, the computer program PFC3D. Blade was moved with angular and transition speed in the positive x-axis direction. For non-vibrating blade only included transition speed and for vibration blade in addition to transition speed, angular velocity was also defined. Working depth was 38 cm and blade speed of 0.89 meters per second was defined. To evaluate the effect of vibration angle on vibrating subsoiler different vibration of 27, 16, 8, zero,-14.5,-22.5 degrees in frequency of 4.9 Hz and amplitude of ± 69 amplitude was tested by simulation. In all vibration tests in comparison with non-vibrating,with Increasing vibration angle (positive and negative), the amount of vertical displacement of blade increased which caused more soil rupture. Simulation results showed that the rate of boundary work, kinetic energy and friction work at positive angles were more than negative vibration angles. With increasing negative angle boundary work and friction work significantly decreased. Changing the angle from -22.5 to 27 degrees decreased average bond energy of particles.