I have a scenario where I have water flowing through a gravel filled pipe, and I need to find the velocity. The pipe is gravity fed (no pumps). My approach is to find the seepage velocity ($V_s$) which is the Velocity divided by the porosity. My understanding is that the seepage velocity is defined as the apparent velocity through the bulk of the porous medium. So that is what I need to find.
I found the velocity using the Darcy Weisbach equation and porosity of gravel from online research, however I am getting a very high value for the seepage velocity (about 56 m/s) even when using the highest porosity value.
Another method that was suggested to me would be to use $Q = KIA$ where $k$ = hydraulic conductivity of gravel, $I$ = hydraulic gradient and $A$ = cross sectional area. However, this condition is only for laminar flow conditions (very slow velocities - such as groundwater under an aquifer. So I don't think I can use this equation. This method gives me a very low velocity which also seems incorrect.
Both methods seem to give me odd values so could anyone assist me with this problem?