CFD Analysis on Extrusion of Slurry in Direct Ink Writing
63
of the extrusion pressure is an essential task, which can be predicted using artificial
neural network (ANN) model with three-layer feed-forward system and this model
provides mean extrusion pressure satisfactorily as compared to experimental result.
The pressure gradient developed in the extrusion process of slurry through the single
screw extruder can be predicted by using a general model which can be developed
by volume conservation equation and further solving for pressure and a special case
also found for this model [12]. It is suggested to use high viscosity materials [13]
such as synthesized Cu paste for screw extruder in fabrication of metal structures
using 3D printing, which decreases the shrinkage factor [14].
In this article, DIW technique is discussed to produce complex three-dimensional
CAD models and to simulate the extrusion behavior of slurry through varying the
screw spindle speed, viscosity, and mass flow rate, CFD analysis has been performed.
In addition, experimental measurement of viscosity of slurry with respect to shear
rate is carried out. Theoretical calculations are performed and compared with CFD
analysis results.
2 CFD Analysis of Slurry Extrusion
2.1 Meshing and Boundary Conditions
The conceptual slurry extruder has been modelled in CATIA V5 platform and simulations are carried out by ANSYS FLUENT V16.2. To perform an internal fluid
flow simulation, the fluid domain has been filled inside the extruder. The assumption
made as incompressible fluid flow analysis and pressure-based solver are chosen
with second-order upwind discretization for convective and diffusive terms. Simulations are performed in the convergence criteria of 1 × 10
−05 for better accuracy.
The moving reference frame is created in the extruder screw section to accomplish
the rotary motion. It took around 3500 simulations for software to converge (Figs. 1
and 2).
The flow domain is meshed with tetrahedral element using ANSYS ICEM tool.
The total number of elements which has been generated in computational grid is
approximately 800,000. The mesh refinement was tested by using orthogonality
and skewness test. The most of the elements are lying in the region of 0.80–0.95
in orthogonality and skewness values of 0.02–0.033. Thus, the mesh refinement is
pretty good to observe the flow characteristics of extruder. Grid independence test is
conducted to accurately predict the pressure.
63
of the extrusion pressure is an essential task, which can be predicted using artificial
neural network (ANN) model with three-layer feed-forward system and this model
provides mean extrusion pressure satisfactorily as compared to experimental result.
The pressure gradient developed in the extrusion process of slurry through the single
screw extruder can be predicted by using a general model which can be developed
by volume conservation equation and further solving for pressure and a special case
also found for this model [12]. It is suggested to use high viscosity materials [13]
such as synthesized Cu paste for screw extruder in fabrication of metal structures
using 3D printing, which decreases the shrinkage factor [14].
In this article, DIW technique is discussed to produce complex three-dimensional
CAD models and to simulate the extrusion behavior of slurry through varying the
screw spindle speed, viscosity, and mass flow rate, CFD analysis has been performed.
In addition, experimental measurement of viscosity of slurry with respect to shear
rate is carried out. Theoretical calculations are performed and compared with CFD
analysis results.
2 CFD Analysis of Slurry Extrusion
2.1 Meshing and Boundary Conditions
The conceptual slurry extruder has been modelled in CATIA V5 platform and simulations are carried out by ANSYS FLUENT V16.2. To perform an internal fluid
flow simulation, the fluid domain has been filled inside the extruder. The assumption
made as incompressible fluid flow analysis and pressure-based solver are chosen
with second-order upwind discretization for convective and diffusive terms. Simulations are performed in the convergence criteria of 1 × 10
−05 for better accuracy.
The moving reference frame is created in the extruder screw section to accomplish
the rotary motion. It took around 3500 simulations for software to converge (Figs. 1
and 2).
The flow domain is meshed with tetrahedral element using ANSYS ICEM tool.
The total number of elements which has been generated in computational grid is
approximately 800,000. The mesh refinement was tested by using orthogonality
and skewness test. The most of the elements are lying in the region of 0.80–0.95
in orthogonality and skewness values of 0.02–0.033. Thus, the mesh refinement is
pretty good to observe the flow characteristics of extruder. Grid independence test is
conducted to accurately predict the pressure.