Dimensioning of a rectangular microchannel

bose

hello everyone,

i am modeling a periodic flow through a rectangular microchannel of 70 micrometers(width).i am kind of novice with regards to fluent and would really really appreciate the answers to the following basic queries:

1.how to specify different dimensions for a microchannel i.e. length in mm but height and width in micrometer. 2.how to specify the symmetry wall condition. 3.how to combine two types of mesh.

waiting eagerly for your reply. thanking you all. bose.