Outflow results do not tally w/ hand-calculation?

Julie

Hi all,

In my model,there are two square outlets at one end of the room each of size 0.6*0.6m And another smaller sqaure outlet at one end of size 0.4*0.4m

ANd a group of four rectangular inlets in the middle of the room each of size 0.2*1m

I am given the values in CMH(cubic meters per hour) of air entering and leaving the room THe four inlets each having 450CMH of air entering, hence a total of 1800CMH entering, The two larger outlets has each 850CMH of air leaving, and the smaller outlet 100CMH air leaving

Hence, the CMH in and out of the room thus balanced.

A quick calculation gives the velocity of air entering at 0.625m/s each and the velocity of air leaving at the two oulets each of 0.655m/s

For the inlets, I specify them as Velocity_inlets and put in value of 0.625m/s in Fluent And for the outlets, I specify them as Outflows, where I put in 0.472 weightage at each of the two larger Outlets and 0.056 at the smaller oulets.

However after iterations, and with the solution converged, I did a display vector of the velocity magnitues. I realised that the velocity at the inlets are only 0.578 m/s each and not the 0.625m/s which I have inputed. And the velocity of at each of the larger outlets is only 0.347m/s and not the 0.655m/s that I have calculated.

Then I did a report/surface integrals/mass flow rate The values computed are in accordance to the my calculations.

I wonder what went wrong, the outlets are supposed to have a higher flow rate 850CMH, and when divided by (60*60) to give CM per sec, and divided by its cross-sectional area should give a value of 0.655m/s as velocity

But the vectors results does not show this. Why?