Why would a parallel circuit (or in blood) decrease resistance

[hongiddong]

Hi PhysicsForums,

Why would a parallel circuit(or in blood) decrease resistance?

Here is my thought experiment and where I got stuck:

Say from aorta to one arteriole, the resistance is super high on that flow(this big amount of flow is entering a tinier area), but add more arterioles and we have a bigger area in total and blood can flow better(but whyyyy) Why would having a greater area conceptually help with the resistance?

 

[NascentOxygen]

For the same total volume flow, more paths in parallel mean that less blood is required to flow through each, and the consequent lower flow rate in each means there is reduced fluid friction to overcome.

 

[ZapperZ]

Hi PhysicsForums,

Why would a parallel circuit(or in blood) decrease resistance?

Here is my thought experiment and where I got stuck:

Say from aorta to one arteriole, the resistance is super high on that flow(this big amount of flow is entering a tinier area), but add more arterioles and we have a bigger area in total and blood can flow better(but whyyyy) Why would having a greater area conceptually help with the resistance?

Look at the continuity equation for fluid flow. See if you can figure out why a larger total flow area means a lower speed for the fluid. Then apply what NascentOxygen has stated.

Zz.

 

[sophiecentaur]

If you define the resistance as rate of flow divided by pressure difference then the flow will double and, thus, your resistance will halve.