630 research outputs found
Constitutive equations for granular flow with uniform mean shear and spin fields
Numerical simulations of two-dimensional granular flows under uniform shear
and external body torque were performed in order to extract the constitutive
equations for the system. The outcome of the numerical simulations is analyzed
on the basis of the micropolar fluid model. Uniform mean shear field and mean
spin field, which is not subordinate to the vorticity field, are realized in
the simulations. The estimates of stresses based on kinetic theory by Lun [Lun,
J. Fluid Mech., 1991, 233, 539] are in good agreement with the simulation
results for a low area fraction but the agreement becomes weaker as
the area fraction gets higher. However, the estimates in the kinetic theory can
be fitted to the simulation results up to by renormalizing the
coefficient of roughness. For a relatively dense granular flow (), the
simulation results are also compared with Kanatani's theory [Kanatani, Int. J.
Eng. Sci., 1979, 17, 419]. It is found that the dissipation function and its
decomposition into the constitutive equations in Kanatani's theory are not
consistent with the simulation results.Comment: 22 pages, 10 figure
Soft x-ray detector array system on the Large Helical Device
Soft x-ray (SX) detector array systems are installed on the Large Helical Device (LHD). Two types of systems are in operation: An 80 ch array for detailed profile measurement and two sets of 40 ch array installed inside the vacuum vessel suitable for fluctuation studies. Recent results of the profile and fluctuation measurement with this system are discussed
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