OLGA 2000 User course – A guided tour

OLGA 2000 – A guided tour

Building an OLGA 2000 case.

This guide leads you through the OLGA 2000 Graphical User Interface in order to

model and run a simple two phase flow case.

Start OLGA 2000.

Select “Case – New”, give your input file the name tour .inp and press “Save”.

The screen below will appear. The message just means that the graphic mimic of the

case can not be drawn yet due to insufficient input. Click OK.

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OLGA 2000 User course – A guided tour

The windows below appear. The "tall" window gives a list of the minimum key words

that must be filled in to make an OLGA case. CASE is the first keyword on this list. Fill

in the PROJECT and TITLE fields. Press the "Close" button and then select (by clicking)

the keyword "OPTIONS" in the "tall" window.

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OLGA 2000 User course – A guided tour

The OPTIONS window has now appeared on your screen. Set TEMPERATURE to WALL

and DEBUG to ON. Close the "OPTIONS" window and then select “FILES” from the

"tall" window. You shall now see the FILES window:

Enter tour.tab in the PVTFILE field. Close the window and select "INTEGRATION".

The INTEGRATION window appears:

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OLGA 2000 User course – A guided tour

Set the following values (the GUI automatically converts a given value when the unit

is changed):

STARTTIME = 0

ENDTIME = 1000 s

CPULIMIT = 1 h

DTSTART = 0.01 s

MINDT = 0.01 s

MAXDT = 20 s

Close the window.

Now, select "Keywords" on the top menu bar and then the sub menu "Geometrical

System Definitions" and then "Material". See the relevant windows below.

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OLGA 2000 User course – A guided tour 5

OLGA 2000 User course – A guided tour

The Material window:

Click “Add” (which is a common requirement for many of the keyword windows) and

insert the following values:

CAPACITY = 500 J/kg-C

CONDUCTIVITY = 50 W/m-K

DENSITY = 7850 kg/m3

Close the window. You will now see that "MATERIAL" is included in the list of

activated keywords in the "tall" window.

Now, select "Keywords" on the top menu bar again and then the sub menu

"Geometrical System Definitions" and this time select "WALL". The WALL window will

now be on your screen.

Press “Add” which activates a pipe wall with the label "WALL-1".

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OLGA 2000 User course – A guided tour

Set the wall MATERIAL to MATERIAL-1 and the material THICKNESS to 0.01 m.

Close window.

Now, try to find the input window for the keyword GEOMETRY/PIPE (see next page).

The GEOMETRY/PIPE window should now be on your screen (if not look under

"Keywords" and then the sub menu "Geometrical System Definitions")

The GEOMETRY-1 is already activated with one pipe. Insert the following values for

PIPE-1:

Elevation = 0

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OLGA 2000 User course – A guided tour

Length = 1000 m

No. of sections (no. of sections that the pipe is divided into ) = 5

Diameter = 8 in

Roughness = 0.0018 in

Wall (Wall label) = WALL-1

Press “Duplicate”.

Select PIPE-2 and modify ELEVATION to 10 m.

Close window.

Select "NODE" from the "tall" window.

Set TYPE to TERMINAL.

Press “Duplicate”. Check that NODE-2 is also of type TERMINAL.

Close

Select "BRANCH".

The BRANCH window will now be on your screen.

Select GEOMETRY-1 for BRANCH-1 which shall start at NODE-1 (FROM) an end at

NODE-2 (TO).

Set fluid to = 1

Close

Select "BOUNDARY".

Specify the inlet boundary to be of type CLOSED at NODE-1.

Press “Add”.

Select the second boundary definition (Index_1). Let this boundary be of type

PRESSURE and attach it to NODE-2.

Give the other BOUNDARY subkeys the following values:

o TIME = 0

o Pressure = 60 bara

o Temperature = 25 °C

o Leave Waterfraction = 0

o Gasfraction = 1

Close the window.

Select "Keywords" on the top menu bar again and this time the sub menu "Boundary

and Initial Conditions" and then "HEATTRANSFER".

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OLGA 2000 User course – A guided tour

Click “Add”. Assume that BRANCH-1 is surrounded by sea water with a temperature

of 5 _C (TAMBIENT)

Set HAMBIENT to 500 W/m2C (the outer wall surface heat transfer coefficient).

Press "Next"

Continue pressing “Next” until the SOURCE window appears.

Press “Add”

Insert SOURCE-1 in BRANCH-1, PIPE-1, and SECTION 1.

TIME = 0

TEMPERATURE = 50 C

MASSFLOW = 10 kg/s

Leave WATERFRACTION = 0 and GASFRACTION = -1 (default values)

Click “Close”.

Now click the "Refresh drawing" button on the lower menu bar to display the system

mimic.

The system mimic is "live" e.g. if you put the pointer on the blue "pipe" and click you

will see the profile of the branch. If you right-click you will see a menu. You can also

click on the nodes and the source.

Select "OUTPUT” from the "tall" window to finish the input of case data.

Print to the output file (ASCII) each 500 seconds (DTOUT).

Print the gas velocity, liquid velocity, holdup, and the flow regime in the whole

branch (BRANCH= BRANCH-1, VARIABLE = UG, UL, HOL, ID)

Press “Next”.

The TREND window will appear.

Plot every 10. s (DTPLOT) the temperature and pressure (TM, PT) at the pipeline

inlet: BRANCH-1, PIPE-1, SECTION 1.

Press “Duplicate” and modify the position to the outlet: BRANCH-1, PIPE-2,

SECTION 5. Add the total mass flow rate (GT) to the variables (in VARIABLE).

Press “Next”.

The PROFILE window will now be on your screen.

Plot every 100. second (DTPLOT) for BRANCH-1. Plot temperature, total liquid

volume flow rate, holdup, and flow regime (VARIABLE = TM, QLT, HOL, ID)

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OLGA 2000 User course – A guided tour

Press “Close”.

You have now created your first case.

Running the OLGA 2000 simulation

Press the button "Run batch" on the lower menu bar. When you start the batch

execution the input file is automatically saved.

All messages to the user is directed to the OLGA 2000 DOS window. When you see

“NORMAL STOP IN EXECUTION” your OLGA 2000 case has completed successfully.

Viewing the simulation results.

Selecting “Profile plot" on the lower menu bar and HOLDUP, BRANCH -1 [-] will

produce a window like the one below. The graph gives the total liquid volume fraction

as function of distance along the branch at time = 0. You may scroll the time in the

"Time [s]" pull down.

You may also add the pipeline profile to the same graph, by clicking the "Add curve"

button and then the "Add pipeline profile" on the next window. The result is given

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OLGA 2000 User course – A guided tour

below.

You may add one or more different variables from the list above to the same profile

graph - e.g. fluid temperature. The result of all this is given below.

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OLGA 2000 User course – A guided tour 12

The trend graph window below is made by selecting “Trend plot” from the lower

menu bar, clicking “Add curve”, and selecting “TOTAL MASS FLOW BRANCH-1, PIPE-2,

5 [kg/s]”. Remember that the Trend plot gives a variable as function of time at a

specific position in the branch (while the Profile plot gives a series of snapshots of an

entire branch).

Congratulations!

You have completed your first OLGA study!