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If automatic time incrementation is not selected in the analysis procedure, values of PNEWDT that are greater than 1.0 will be ignored and values of PNEWDT that are less than 1.0 will cause the job to terminate.

# ENER

Energy per unit mass stored in the fluid. This variable is used for energy output only and has no effect on the solution.

# Variables passed in for information

# PRESS

Fluid cavity pressure at the end of the increment. For a linear perturbation step this is the base state pressure.

# DPRESS

Fluid cavity pressure increment. For a linear perturbation step this value is zero.

# PRESSI

Fluid cavity pressure at the beginning of the analysis.

# TEMP

Fluid cavity temperature at the end of the increment. For a linear perturbation step this is the base state temperature.

# DTEMP

Fluid cavity temperature increment. For a linear perturbation step this value is zero.

# TEMPI

Fluid cavity temperature at the beginning of the analysis.

# TIME(1)

Current value of step time at the start of the increment.

# TIME(2)

Current value of total time at the start of the increment.

# DTIME

Time increment.

# KSTEP

Step number.

# KINC

Increment number.

# NONUM

Cavity reference node number.

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# FLNAME

User-specified fluid property name, left justified.

# LFLAG

Linear perturbation flag for the step. If this is a linear perturbation step, LFLAG=1. For a general analysis step LFLAG=0.

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# 1.1.34 UFLUIDCONNECTORLOSS: User subroutine to define the loss coefficient for fluid flow in fluid pipe connector elements.

Product: Abaqus/Standard

# Reference

• \*FLUID PIPE CONNECTOR LOSS

# Overview

User subroutine UFLUIDCONNECTORLOSS:

• can be used to define the loss coefficient in a fluid pipe connector element;   
• corresponds to the Darcy-Weisbach equation for pressure loss; and   
• can be used with the fluid pipe connector elements.

# User subroutine interface

```txt
subroutine ufluidconnectorloss (
C Write only -
* ak1, ak2,
C Read only -
* coords, flow, rho, visc,
* dia, area,
* ndim, jelno, kStep, kInc,
* time,
* nIarray,
* i_array,
* nRarray,
* r_array,
* ncarray,
* c_array)
C
include 'aba_param.inc'
C
dimension time(2),
* coords(2*ndim),
* i_array(nIarray),
* r_array(nRarray)
C
character*80 c_array(ncarray) 
```

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C

```lua
user coding to define connector friction values
return
end 
```

# Variables to be defined

ak1

This connector loss coefficient must be updated and is used when the flow is from node 1 to node 2.

ak2

This connector loss coefficient must be updated and is used when the flow is from node 2 to node 1.

# Variables passed in for information

coords(2\*ndim)

Array containing original coordinates of the element. coords(1:ndim) is the coordinate of the first node, and coords(ndim+1:2\*ndim) is the coordinate of the second node.

flow

Current flow rate through the element.

rho

Current density of fluid flowing through the pipe.

visc

Current viscosity of fluid flowing through the pipe.

dia

User-specified hydraulic diameter.

area

User-specified hydraulic area.

ndim

Dimension of the element.

jelno

User element number for which friction coefficient is required.

kStep

Step number.

kInc

Increment number.

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time(1)

Current step time.

time(2)

Total time.

nIarray

Size of array i\_array.

i\_array

Integer array for future expansion.

nRarray

Size of array r\_array.

r\_array

Real array for future expansion.

ncarray

Size of array c\_array.

c\_array

Character array for future expansion.

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# 1.1.35 UFLUIDCONNECTORVALVE: User subroutine to define the valve opening to control flow in fluid pipe connector elements.

Product: Abaqus/Standard

# Reference

• \*FLUID PIPE CONNECTOR LOSS

# Overview

User subroutine UFLUIDCONNECTORVALVE:

• can be used to control the valve opening to turn off or turn on fluid flow; and   
• can be used with fluid pipe connector elements.

# User subroutine interface

```txt
subroutine ufluidconnectorvalve (
C Write only -
* valveOpening,
C Read only -
* coords, flow, rho, visc,
* dia, area,
* ndim, jelno, kStep, kInc,
* time,
* nIarray,
* i_array,
* nRarray,
* r_array,
* ncarray,
* c_array)
C
    include 'aba_param.inc'
C
    dimension time(2),
* coords(2*ndim),
* i_array(nIarray),
* r_array(nRarray)
C
    character*80 c_array(ncarray)
C 
```

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```lua
user coding to define control valve opening
return
end 
```

# Variable to be defined

valveOpening

The value of this variable must be set between 0.0 (closed/shut-off) and 1.0 (fully open) to determine whether the valve is fully or partially open or closed.

# Variables passed in for information

coords(2\*ndim)

Array containing the original coordinates of the element. acoords(1:ndim) is the coordinate of the first node, and acoords(ndim+1:2\*ndim) is the coordinate of the second node.

flow

Current flow rate through the element.

rho

Current density of fluid flowing through the pipe.

visc

Current viscosity of fluid flowing through the pipe.

dia

User-specified hydraulic diameter.

area

User-specified hydraulic area.

ndim

Dimension of the element.

jelno

User element number for which a friction coefficient is required.

kStep

Step number.

kInc

Increment number.

time(1)

Current step time.

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time(2)

Total time.

nIarray

Size of array i\_array.

i\_array

Integer array for future expansion.

nRarray

Size of array r\_array.

r\_array

Real array for future expansion.

ncarray

Size of array c\_array.

c\_array

Character array for future expansion.

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