Computational Investigation of Various Transition Stages in the Drop Formation Process

This article presents a complementary experimental and computational investigation of the effect of viscosity and flowrate on the dynamics of drop formation in the dripping mode. In contrast to previous studies, numerical simulations are performed with two popular commercial computational fluid dynamics (CFD) packages, CFX and FLOW-3D, both of which employ the volume of fluid (VOF) method. Comparison with previously published experimental and computational data and new experimental results reported here highlight the capabilities and limitations of the aforementioned packages.

Download Full-text

Analysis of Drop-on-Demand Ink Jet Print Head for Rapid Prototyping

MRS Proceedings ◽

10.1557/proc-698-q4.5.1 ◽

2001 ◽

Vol 698 ◽

Author(s):

Dong-Youn Shin ◽

Paul Grassia ◽

Brian Derby

Keyword(s):

Rapid Prototyping ◽

Formation Process ◽

Stokes Equations ◽

Navier Stokes ◽

Hydrodynamic Characteristics ◽

Drop Formation ◽

Print Head ◽

Drop On Demand ◽

Ink Jet ◽

The Operating Mechanism

ABSTRACTThe rapid prototyping industry is growing dramatically because of its high potential to reduce product design and prototyping cycles. One of the recent technologies in this field is 3D printing using conventional ink jet technology. In order to maximize the capability of this process, it is required to understand the operating mechanism and drop formation process. The current work focuses on the mechanism of a piezoelectric cylindrical actuator and the hydrodynamic characteristics inside a print head in order to achieve more realistic boundary conditions for the numerical simulation of the drop formation process. Linearised Navier-Stokes equations for Newtonian fluid flow are solved analytically for the pump section with a constant radius and for the nozzle section with a tapering angle. Results from the developed solutions are input to Flow 3D and it is observed that analytical pressure histories show better agreement with numerical results than axial velocity histories. The presented analytic model can be used for fully further drop formation simulation as an upstream pressure boundary within an acceptable tolerance.

Download Full-text

Formation process of periodic non-conservative antiphase boundary structure in L-Pd5Ce

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100173947 ◽

1990 ◽

Vol 48 (4) ◽

pp. 162-163

Author(s):

Masaru Itakura ◽

Noriyuki Kuwano ◽

Kensuke Oki

Keyword(s):

Formation Process ◽

Domain Size ◽

Antiphase Boundary ◽

Boundary Structure ◽

Temperature Phase ◽

Arc Melting ◽

Iced Water ◽

Antiphase Domains ◽

Low Temperature Phase ◽

Degree Of Order

The low temperature phase of Pd5Ce (L-Pd5Ce) has a one-dimensional long period superstructure (1D-LPS) derived from Ll2. The periodic antiphase boundaries (APBs) are parallel to (110) planes and have a shift vector of 1/2[110]. Hereafter, the indices are referred to the basic lattices of Ll2 As insertion of the APB causes a change in composition, such an APB is called “non-conservative”. Then, a domain size M depends upon the Ce concentration in the alloy. It was found that M increases also with temperature. The temperature dependency of M is attributed to a change of the degree of order within the antiphase domains. In this work, morphology of the non-conservative APBs is observed to clarify the formation process of the 1D-LPS.The alloy of Pd-16.7 at%Ce was prepared by arc melting in argon atmosphere. Disc specimens made from the alloy ingot were first held at 985 K for 260 ks and quenched in iced water to obtain the state of M=∞ or Ll2, followed by annealing for various lengths of time. The annealing temperature was 873 K where the equilibrium value for M is about 3 in unit of (110) lattice spacing of Ll2. Observation was carried out using microscopes JEM-2000FX, JEM-4000EX (HVEM Lab., Kyushu Univ.) and JEM-2000EX (Dept. of Mater. Sci. Tech., Kyushu Univ.).

Download Full-text