gravitational acceleration in laminar pipe flow
 

i`m modeling a horizontal pipe with laminar flow... the solver is set to Discrete Phase Model, as i m` also simulating the injection of nano-sized particles with the base fluid ( water)....i`m at doubt as to what is the value of gravitational acceleration that i shud set in the operating conditions tab ( both the X and Y components)..... i don think it can be 9.81..pls help....:confused: