Head loss function of velocity^2 or velocity^1?
 

Is head loss due to flow expansion/contraction a function of velocity or velocity^2 under laminar conditions?

i.e., in the Bernoulli's eqn, should one write Kv^2/2g or Kv/2g? I know that the K for a long pipe is proportional to 1/Re leading to a dependence only on v. But I'm not sure about minor losses.

Re: Head loss function of velocity^2 or velocity^1
 

You should always use K*V^2/2g. However for low Re K can be a function of Re. For expansion/contraction it is so complicated that I will not post it here, because I can mistype :)