SWMM-USERS Digest - 17 Dec 2009 to 21 Dec 2009 (#2009-139)

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Dec 22, 2009, 12:03:43 AM12/22/09

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There are 6 messages totalling 674 lines in this issue.

Topics of the day:

1. Max/Full flow definitions in PCSWMM
2. Max/Full flow definitions in SWMM5 - reply(1) (2)
3. Conduit under tidal influence
4. Multiple Box Culvert Inlet Outlet losses (2)

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Date: Mon, 21 Dec 2009 09:17:08 -0800
From: Jason Barta <jba...@URBAN-SYSTEMS.COM>
Subject: Max/Full flow definitions in PCSWMM

I am running a hydraulic analysis of a sanitary sewer system in PCSWMM
(5.0.017)

There are certain pipe segments that are identified as being full at
both ends for a certain duration.

The ratio "Max/Full Flow" is greater than 1 in these instances, but the
ratio "Max/Full Depth" is less than 1 (0.6 to 0.97)

=20

Can anyone explain how SWMM quantifies these 4 terms?

Max Flow

Full Flow

Max Depth

Full Depth

=20

Best regards,

Jason

=20

Disclaimer :

The information transmitted is intended only for the person or entity to =
which it is addressed and may contain confidential and/or privileged mate=
rial. Any review, transmission, dissemination or other use of, or taking =
of any action in reliance upon, this information by persons or entities o=
ther than the intended recipient is prohibited. If you received this in e=
rror, please contact the sender and delete the material from any computer=
s.

------------------------------

Date: Mon, 21 Dec 2009 11:08:01 -0700
From: Robert Dickinson <Robert.E....@US.MWHGLOBAL.COM>
Subject: Re: Max/Full flow definitions in SWMM5 - reply(1)

Hi Jason,

Max Flow is the maximum flow in the link during the simulation,

Full Flow is the full flow of the link as calculated from the full link are=
a, full hydraulic radius, roughness and the slope of the link.

Max Depth is the maximum depth in the link during the simulation.

Full Depth is the maximum diameter of a closed pipe or the maximum depth in=
an open channel.

Now your question is " The ratio "Max/Full Flow" is greater than 1 in these=
instances, but the ratio "Max/Full Depth" is less than 1 (0.6 to 0.97)"

... the depth of the pipe can be less than the diameter of the pipe at the =
same time the max flow in the pipe can be greater than the full flow in the=
pipe because the pipe flow in SWMM 5 is based on the equation:

dQ/dt + d(Q^2/A)/dx + gAdy/dx + gA(Sf + So + Sother + Sexit + Sentrance) =
=3D 0

where, d =3D is actually the partial derivative,

A =3D the cross sectional area,

Q =3D flow in the link,

t =3D time

x =3D link length,

y =3D link depth,

g =3D gravity constant,

Sf =3D friction loss,

Sother =3D other loss,

So =3D bed slope,

Sexit =3D exit loss, and

Sentrance =3D entrance loss.

The water surface slope term + the bed slope term + the non-linear term can=
allow the pipe to handle more than the full flow at pipe depths less than =
the pipe diameter. The full flow comparison term only includes the bed slo=
pe term.

Best and Kind Regards,

Robert Dickinson

SW/WW Technical Engineering Specialist

MWH Soft, Inc

9340 Pontiac Drive Tel: 813-712-0664

Tampa, Florida, 33626 Alt: 813-494-2919

USA

robert.d...@mwhsoft.com

www.mwhsoft.com

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@listserv.uoguelph.ca] On Behalf Of Jaso=
n Barta
Sent: Monday, December 21, 2009 12:17 PM
To: SWMM-...@listserv.uoguelph.ca
Subject: [SWMM-USERS] Max/Full flow definitions in PCSWMM

I am running a hydraulic analysis of a sanitary sewer system in PCSWMM

(5.0.017)

There are certain pipe segments that are identified as being full at

both ends for a certain duration.

The ratio "Max/Full Flow" is greater than 1 in these instances, but the

ratio "Max/Full Depth" is less than 1 (0.6 to 0.97)

Can anyone explain how SWMM quantifies these 4 terms?

Max Flow

Full Flow

Max Depth

Full Depth

Best regards,

Jason

Disclaimer :

The information transmitted is intended only for the person or entity to wh=
ich it is addressed and may contain confidential and/or privileged material=
. Any review, transmission, dissemination or other use of, or taking of any=
action in reliance upon, this information by persons or entities other tha=
n the intended recipient is prohibited. If you received this in error, plea=
se contact the sender and delete the material from any computers.

**********************************************************

* To sign off, email to: list...@listserv.uoguelph.ca *

* In the body of the message type: signoff swmm-users *

**********************************************************

------------------------------

Date: Mon, 21 Dec 2009 18:58:45 +0000
From: Francisco Araujo <f...@COBA.PT>
Subject: Conduit under tidal influence

Hello all,
I'm modeling a stormwater conduit that's under tidal influence. I just want=
ed to test the worst possible condition so I set a fixed type tide at 2 met=
ers at the outfall with no flap gate, and inserted 3 constant flows in 3 di=
fferent nodes, adding up to 6.03 CMS. The outfall is completely "drowned": =
IE=3D-1.69, square conduit with 2 meters side.
The simulation ran well, and I had a continuity error 0.05%.
I noticed some initial instability in the early moments of the simulation w=
ith the HGL peaking causing some unexpected floods in upstream nodes, and t=
hen the HGL stabilized to the expected level. Then I tried a different appr=
oach, releasing the flows 15 min after the start of the simulation in order=
to allow for the conduit to fill with tidal water, before it had to handle=
the flows. I noticed some peaks in the HGL when the conduit was filling, c=
ausing floods, well over the 2 meters of set tide, and the flows hadn't eve=
n "kicked in".
Basically I'm having difficulty interpreting the results in the early momen=
ts of simulation. Are the peaks caused by actual hydraulic effects? Should =
I neglect these early peaks and focus on the results of the simulation, aft=
er the HGL has stabilized (asking for a report only on later stages of the =
simulation)?
On the other hand, is it possible to introduce local head losses in SWMM, s=
uch as curves, once I'm working with (slightly) pressurized flow? Does SWMM=
calculate them automatically?
I hope my questions are clear enough.
Thanks in advance,
Best regards,
Francisco Araujo

------------------------------

Date: Mon, 21 Dec 2009 16:03:06 -0500
From: Rob James <r...@COMPUTATIONALHYDRAULICS.COM>
Subject: Re: Max/Full flow definitions in SWMM5 - reply(1)

Jason,

The reported full flow of the conduit is calculated from the Manning's formula (as a conduit property, not a simulation result) and is supposed to be an indication of the pipe's design flow. However since this calculation is based on an assumption of steady uniform flow, the flow through the pipe can exceed this value under a number of circumstances. Also, recall that the maximum uniform steady flow through a circular pipe occurs when the water depth (y) is less than full depth (d) - at y/d ~ 0.94 - due to increasing friction as the wetted perimeter increases. I believe the SWMM5 reported full flow of a conduit is calculated at y/d = 1.

The calculated full flow for each conduit is reported in the Cross Section Summary section of the status report, when the Report Input Summary option is turned on.

Sincerely,

Rob James
Computational Hydraulics Int. (CHI)
www.computationalhydraulics.com
Tel. 1-519-767-0197

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@listserv.uoguelph.ca] On Behalf Of Robert Dickinson
Sent: December-21-09 1:08 PM
To: SWMM-...@listserv.uoguelph.ca
Subject: Re: [SWMM-USERS] Max/Full flow definitions in SWMM5 - reply(1)

Hi Jason,

Max Flow is the maximum flow in the link during the simulation,

Full Flow is the full flow of the link as calculated from the full link area, full hydraulic radius, roughness and the slope of the link.

Max Depth is the maximum depth in the link during the simulation.

Full Depth is the maximum diameter of a closed pipe or the maximum depth in an open channel.

Now your question is " The ratio "Max/Full Flow" is greater than 1 in these instances, but the ratio "Max/Full Depth" is less than 1 (0.6 to 0.97)"

... the depth of the pipe can be less than the diameter of the pipe at the same time the max flow in the pipe can be greater than the full flow in the pipe because the pipe flow in SWMM 5 is based on the equation:

dQ/dt + d(Q^2/A)/dx + gAdy/dx + gA(Sf + So + Sother + Sexit + Sentrance) = 0

where, d = is actually the partial derivative,

A = the cross sectional area,

Q = flow in the link,

t = time

x = link length,

y = link depth,

g = gravity constant,

Sf = friction loss,

Sother = other loss,

So = bed slope,

Sexit = exit loss, and

Sentrance = entrance loss.

The water surface slope term + the bed slope term + the non-linear term can allow the pipe to handle more than the full flow at pipe depths less than the pipe diameter. The full flow comparison term only includes the bed slope term.

Best and Kind Regards,

Robert Dickinson

SW/WW Technical Engineering Specialist

MWH Soft, Inc

9340 Pontiac Drive Tel: 813-712-0664

Tampa, Florida, 33626 Alt: 813-494-2919

USA

robert.d...@mwhsoft.com

www.mwhsoft.com

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@listserv.uoguelph.ca] On Behalf Of Jason Barta
Sent: Monday, December 21, 2009 12:17 PM
To: SWMM-...@listserv.uoguelph.ca
Subject: [SWMM-USERS] Max/Full flow definitions in PCSWMM

I am running a hydraulic analysis of a sanitary sewer system in PCSWMM

(5.0.017)

There are certain pipe segments that are identified as being full at

both ends for a certain duration.

The ratio "Max/Full Flow" is greater than 1 in these instances, but the

ratio "Max/Full Depth" is less than 1 (0.6 to 0.97)

Can anyone explain how SWMM quantifies these 4 terms?

Max Flow

Full Flow

Max Depth

Full Depth

Best regards,

Jason

Disclaimer :

The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, transmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from any computers.

**********************************************************

* To sign off, email to: list...@listserv.uoguelph.ca *

* In the body of the message type: signoff swmm-users *

**********************************************************

------------------------------

Date: Tue, 22 Dec 2009 12:27:09 +1100
From: Kuhan Kuhanesan <Kuhan.K...@D2G.COM.AU>
Subject: Multiple Box Culvert Inlet Outlet losses

Hi,

=20

In SWMM, I am modelling a culvert crossing a small creek consisting of
five large box culverts (RCBCs) each 3.3m wide and 1.8m depth. What
are the best values for the inlet and outlet loss factors to be used to
model these multiple box culverts? Any references please?

=20

Thanks

=20

Regards

=20

Kuhan Kuhanesan=20
Drainage Engineer=20

=20

P 07 3280 9395

F 07 3280 9111

E Kuhan.K...@d2g.com.au <mailto:Kuhan.K...@d2g.com.au> =20

Chalk Street, Redbank Q 4301
PO BOX 505, Booval Business Centre Q 4304

Safe Work, Safe Travel, Safely Home=20

lThink before you print, embrace the green office l

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------------------------------

Date: Mon, 21 Dec 2009 20:54:51 -0500
From: "Heineman, Mitchell" <Heine...@CDM.COM>
Subject: Re: Multiple Box Culvert Inlet Outlet losses

Kuhan - I typically use US Highway Administration Hydraulic Engineering
Circular No. 22, URBAN DRAINAGE DESIGN MANUAL to obtain values of this
sort. Table 7-5b. Coefficients for Culverts; Outlet Control, Full or
Partly Full should have what you're looking for.

This, various other helpful documents, on-line calculators, etc for SWMM
modeling are referenced at www.dynsystem.com/netstorm/cdmuswmm.htm

Mitch Heineman, P.E., D. WRE, BCEE
Associate | Collector Systems and Surface Water Subdiscipline Leader
CDM
50 Hampshire Street
Cambridge MA 02139

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@listserv.uoguelph.ca] On Behalf Of
Kuhan Kuhanesan
Sent: Monday, December 21, 2009 8:27 PM
To: SWMM-...@listserv.uoguelph.ca
Subject: [SWMM-USERS] Multiple Box Culvert Inlet Outlet losses

Hi,

Thanks

Regards

Kuhan Kuhanesan
Drainage Engineer

------------------------------

End of SWMM-USERS Digest - 17 Dec 2009 to 21 Dec 2009 (#2009-139)
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