about stepped spillway
 

hello my friends
i have some questions about stepped spillway
my mudel has over 80 steps and i have to use multi-block
for exapmle this picture:

http://up5.iranblog.com/images/17051756821208918001.jpg

1-should i always use "symmetry" between linked block?
2-what options do i use in "physics"tab?i always use "gravity"& "viscosity and turbulence" for this simulation.what do you idea about another options?
for exapmle, "air entrainment" or "bubble and phase change"?

i hope your guidance
best regards.