# Hydraulic analysis with split and joint

I’m having trouble running a rather simple example of a hydraulic pipe system with 1 split and 1 joint

Running the example gives me

`````` *ERROR in envtemp:
*****number of network equations is not equal to
number of active degrees of freedom*****
# of network equations =           20
# of active degrees of freedom=           18
``````

If I try reducing the # of network equations via removing `*BOUNDARY` with pressure in the nodes of split and joint elements (4 and 19 respectively), I’m getting another error: (I don’t know any other way to remove network equations without changing the structure of the pipe system)

`````` *ERROR in preinitialnet:
node           4  belongs to more than 2 network elements, yet
no initial pressure was assigned
*ERROR in preinitialnet:
node          19  belongs to more than 2 network elements, yet
no initial pressure was assigned
``````

(On a side note, why the pressures in nodes 4 and 19 are needed? Shouldn’t the pressures at INLET and OUTLET be enough?)
I’m not very proficient with pipe systems and was trying to guess what to change in the .inp file for it to give me any results, but failed. What do I need to do, to make my example work?

Here is the picture of it:

Here is the .inp, with which I’d like to get any result

``````*NODE,NSET= NALL
1, 1, 0, 0
2, 2, 0, 0
3, 3, 0, 0
4, 4, 0, 0
5, 5, -0.5, 0
6, 6, -1, 0
7, 7, -1.5, 0
8, 8, -2, 0
9, 5, 0.5, 0
10, 6, 1, 0
11, 7, 1.5, 0
12, 8, 2, 0
13, 9, 1.5, 0
14, 10, 1, 0
15, 11, 0.5, 0
16, 9, -1.5, 0
17, 10, -1, 0
18, 11, -0.5, 0
19, 12, 0, 0
20, 13, 0, 0
21, 14, 0, 0
22, 15, 0, 0
*ELEMENT, TYPE=D,ELSET=AGAS
2,  2,  3,  4
11, 19, 20, 21
*ELEMENT, TYPE=D,ELSET=BGAS
3,  4,  5,  6
5,  4,  9, 10
*ELEMENT, TYPE=D,ELSET=CGAS
4,  6,  7,  8
6,  10, 11, 12
7, 12, 13, 14
8, 8, 16, 17
*ELEMENT, TYPE=D, ELSET=DGAS
9, 14, 15, 19
10, 17, 18, 19
*ELEMENT, TYPE=D,ELSET=DIO
1,  0,  1,  2
12, 21, 22, 0
*MATERIAL,NAME=GAS
*CONDUCTIVITY
50.,0.
*SPECIFIC GAS CONSTANT
287
*DENSITY
1.E-12
*FLUID CONSTANTS
0.1002353938D+4, 0.1711000000D-04
*FLUID SECTION,MATERIAL=GAS,ELSET=AGAS,TYPE=ORIFICE
962,34.99
*FLUID SECTION,MATERIAL=GAS,ELSET=BGAS,TYPE=BRANCH SPLIT GE
2,3,5,600,600,600,45,45
*FLUID SECTION, MATERIAL=GAS, ELSET=DGAS, TYPE=BRANCH JOINT GE
11,9,10, 600,600, 45,45
*FLUID SECTION,MATERIAL=GAS,ELSET=CGAS,TYPE=ORIFICE
314,19.99
*FLUID SECTION,MATERIAL=GAS,ELSET=DIO,TYPE=INOUT
*BOUNDARY
2, 2, 2, 0.3
21, 2, 2, 0.04
19, 2, 2, 0.06
4, 2, 2, 0.2
*STEP