Validation of result (coarse mesh, icoFoam)
 

I'm fairly new to CFD in general, but I have the most basic knowledge of Fluent. However, I am way more interested in OpenFOAM which I have used to get the result in the gif below.

This is a mesh I got in incompressible/icoFoam/elbow, so I'm pretty sure you are familiar with it. The thing is, the main stream has the velocity of 1 m/s, and the auxiliary flow, I made begin with 3 m/s and suddenly drop to 0.1 m/s, and I got this result. Which I'm not sure if it's real or not.

I think it *is* possible for a whole-domain velocity drop, but like this?

What do you think, is it possible? Is this solution real? I know it's a really coarse mesh, but that shouldn't matter (too much), right?

http://s30.postimg.org/ddj7l7ash/elbow0.gif

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Also, I'd like your comment on something; I started this simulation with 1 m/s main stream and 3 m/s auxiliary flow for 100 seconds. Then, I opened the folder "51" and opened "U". There was a list of numbers (velocity distributions in cells, right?), at the end of which were the boundary conditions from "0", so THERE I replaced a 3 with a 0.1. I wanted to reduce the flow in 51st second from 3 m/s to 1 m/s. I also deleted the "phi" folder. The phi is some sort of volumetric flow [m^3/s] but what does it do? I mean shouldn't phi be the general term which becomes ux or uy or uz in Momentum equation? I'm confused with that phi.

Then I resumed the flow from "latestTime" (in controlDict).

Thank you very much for helping a new guy!