Big in Japan
Reproduced in English from an original Japanese interview conducted by Shuichi Ogawa for CDaJ

The first in a series of articles that explores how CD-adapco’s software is used in some of Japan’s most successful companies.

Mitsubishi Chemical Corporation is one of Japan’s leading diversified chemicals companies and is a long time investor in CFD research, particularly in the complex fields of two-phase flow and chemical reaction.

The use of CFD at Mitsubishi has spread rapidly since the early nineties. Starting from a single installation at the Mitsubishi Research Institute in Yokohama, CFD is now used in Mitsubishi plants across the whole of Japan, including Kajima, Yokkaichi, Mizushima and Kurosaki.

“We quickly realized, that to accurately handle the diverse issues that arise at each particular location, it is more effective to implement CFD at every plant that has analytical needs”, says Hiroaki Nagai, an Engineer in Mitsubishi’s Computer Aided Modeling and Simulation Lab in Kurosaki. “In the beginning, CFD was used largely for trouble-shooting within the Kurosaki Plant, but awareness in the field eventually grew to the point where implementation expanded to such areas as preliminary inspections prior to plant construction, and our license usage
rapidly increased.”

More than half of the analysis conducted at the Kurosaki Plant is focused on tank stirring, with some 70-80% concerning multiphase analysis. In simulating these problems Mitsubishi engineers employ Lagrangian, Eulerian or free-surface modeling, each method being used in about a third of cases. Since no ‘off-the-shelf’ empirical data is available for many of Mitsubishi’s chemical reactions (particularly those to do with polymerization), the Kurosaki group maintains a process and
design lab that is equipped with the reaction analysis technology required for determining reaction speed from experiments and operation data. In order to derive reaction parameters for the CFD model, testing samples are actually mixed in a beaker and the test data processed analytically, often reducing the many reactions down to the few most important. Reaction parameters are then integrated into STAR-CD using user subroutines.

"In a word, the robustness of the software is amazing with the powerful user subroutines, we are able to perform a wide range of complex analysis. “

Mitsubishi originally adopted STAR-CD in Kurosaki because of the strength of its meshing generation process and its ability to construct unstructured meshes quickly and easily. “I like the ease with which models can be created and, should any occur, it is also easy to correct problems with the mesh quality”, says Mitsubishi Engineer Masaru Futagawa. Through many years of usage they have also come to depend on the strength and robustness of its solver: “Compared to other software, convergence is superior”, says Nagai. “In a word, the robustness of the software is amazing and with the powerful user subroutines, we are able to perform a wide range of complex analyses.”

In addition to tank stirring simulations, Mitsubishi’s CFD Engineers are regularly called upon to conduct other types of CFD simulation in support of plant activities. Recently they have been involved in modeling smoke dispersion in the plant, and an analysis of a wastewater purification tank.

The team at Kurosaki has also successfully completed extensive CFD analyses of a granulation tower at the plant, a device that forms powder from molten droplets of liquid as they fall into a plume of cold air. “The Lagrangian two-phase flow function was used to the fullest extent in this analysis, providing extremely interesting results”, says Nagai.