# zone fluid command

Syntax

zone fluid keyword

Primary keywords:

This command sets parameters for a groundwater fluid flow analysis. These commands are only available after a model configure fluid command. These parameters apply to zones only, other model elements may have different values.

active b

The fluid process is on for zones, by default, when the model configure fluid command is given. Specify active off to suppress the fluid calculation for zones. Generally this command is unnecessary and is slaved to the zone fluid active setting.

biot b

The fluid-flow calculation uses the Biot coefficient, $$α$$, and the Biot modulus, $$M$$, if on. If off, then the fluid modulus, $$K_f$$ , and porosity, $$n$$, are used and $$α$$ = 1. The default is off. See Biot Coefficient and Biot Modulus.

cmodel keyword

Associates a fluid constitutive model with specified zones in the grid. It also allows querying of properties and states of constitutive models.

assign keyword <range>

assigns a fluid model to all zones in the range. This keyword may only be given if the model is configured for fluid calculations (see model configure fluid). Fluid models are described in Grid Configured for Fluid Flow.

anisotropic

Assign the anisotropic flow model.

isotropic

Assign the isotropic flow model.

null

Assign the null fluid model.

list

List the available fluid constitutive models and their properties.

fastflow b

Turns the fastflow solution scheme on and off. See Fully Saturated Fast Flow.

fastflow-relaxation f

Sets the relaxation parameters used in the fastflow solution scheme.

implicit b

The implicit solution scheme in the fluid flow model is turned on or off. The default is off.

list
information

Outputs current configuration settings and status information for the fluid model.

property keyword <range>

Outputs the values of the specified fluid property in all zones in the range.

biot f

Biot coefficient (grain compressibility), $$\alpha$$. The default is 1.0.

porosity f

Porosity, $$n$$. The default is 0.5.

undrained-thermal-coefficient f

Undrained thermal coefficient, $$\beta$$.

permeability f

Isotropic permeability, $$k$$. The permeability used in FLAC3D is defined as the conventional hydraulic Permeability divided by the unit weight of water. Permeability must be non-zero if the command zone fluid active on applies.

dip f

Principal permeability plane dip angle (in degrees).

dip-direction f

Principal permeability plane dip direction angle (in degrees).

permeability-1 f

Principal permeability value.

permeability-2 f

Principal permeability value.

permeability-3 f

Principal permeability value.

permeability-xx f

xx-component permeability.

permeability-xy f

xy-component permeability.

permeability-xz f

xz-component permeability.

permeability-yy f

yy-component permeability.

permeability-yz f

yz-component permeability.

permeability-zz f

zz-component permeability.

rotation f

Principal permeability plane rotation angle (in degrees).

property keyword ... <range>

Assigns properties for the fluid flow constitutive models of all zones in the rnage. Any number of name value pairs may be assigned. The type of the value a must match the type expected by the property s. Any constitutive model that has a matching property name will be assigned the value.

biot f

Biot coefficient (grain compressibility), $$\alpha$$. The default is 1.0.

porosity f

Porosity, $$n$$. The default is 0.5.

undrained-thermal-coefficient f

Undrained thermal coefficient, $$\beta$$.

Isotropic Fluid Flow:

permeability f

Isotropic permeability, $$k$$. The permeability used in FLAC3D is defined as the conventional hydraulic Permeability divided by the unit weight of water. Permeability must be non-zero if the command zone fluid active on applies.

Anisotropic Fluid Flow:

dip f

Principal permeability plane dip angle (in degrees).

dip-direction f

Principal permeability plane dip direction angle (in degrees).

permeability-1 f

Principal permeability value.

permeability-2 f

Principal permeability value.

permeability-3 f

Principal permeability value.

permeability-xx f

xx-component permeability.

permeability-xy f

xy-component permeability.

permeability-xz f

xz-component permeability.

permeability-yy f

yy-component permeability.

permeability-yz f

yz-component permeability.

permeability-zz f

zz-component permeability.

rotation f

Principal permeability plane rotation angle (in degrees).

property-distribution s akeyword ... <range>

Assigns a single property name to the fluid flow constitutive models of all zones in the range. The property value may be varied in space by using the following optional keyword values.

Add a to the property value. This keyword only applies to float type property values.

deviation-gaussian f

A gaussian distribution is used to assign the value randomly, with a mean value of a and a standard deviation of f. This keyword only applies to float type property values.

deviation-uniform f

A uniform distribution is used to assign the value randomly, with a mean value of a and a standard deviation of f. This keyword only applies to float type property values.

Apply a gradient to the property value. This keyword only applies to float type property values.

multiply

Multiply the property value by a.

vary v

Apply a linear variation to the property value. This keyword only applies to float type property values.

saturation-tolerance f

The effect of saturation changes to gridpoints is only applied when the accumulated saturation change is greater than this value. This is done for efficiency of calculation. The default value is 1x10:exp:$$-3$$

time-total f

Specifies the accumulated zone fluid time, defined as the sum of all the timesteps over which zone fluid is active. Once set, fluid time will continue to accumulate with subsequent cycles.

track keyword

The TRACK command places a particle in the grid at the location specified. The particle flows with the fluid and maintains a record of its path over a finite period of time. The grid must be configured for fluid flow (see model configure fluid), and the zone must have a non-null fluid model in order for a particle to exist in a zone. The particle is not created (and no error message is output) if the location does not map into a zone with these specifications. The particles have no mass and do not influence the flow or mechanical behavior in any way; they are simply carried along by the fluid and record its motion. Several TRACK commands may be given, at different times, if desired. See the data files in One-Dimensional Filling of a Porous Region for an example of particle track usage. Location and keywords are given as follows.

active b

Turns particle tracking on or off. track is off by default.

create keyword

Create one or more particles in zones. The location and number of the particles created are controlled by the following keywords. The <[zonefluidblock]> following can be used to specify attributes on the created particles.

point v ...

Place a particle in the grid at the specified location v. For each vector value given, another particle will be created.

line keyword ...

Add particles to the grid along a line.

begin v

Specify the start position of the line. The default value is (0,0,0).

end v

Specify the end position of the line. The default value is (0,0,0).

segment i

Specify the line be divided equally into i + 1 segments, causing i particles to be introduced into the grid. The default value is 2.

plane keyword ...

Add particles to the grid along a plane defined by two lines.

begin v

Specifies the shared start point of both lines that will define the plane. The default value is (0,0,0).

end-1 v

Specifies end of the first line. The default value is (0,0,0).

end-2 v

Specifies end of the second line. The default value is (0,0,0).

segment i1 i2

Divides the first line into i1 + 1 equal segments; divides the second line into i2 + 1 equal segments. i1 x i2 particles will be introduced to the grid on an evenly spaced grid along the plane. The default value of i1 and i2 is 2.

delete <range>

Delete particles within the given range

group s keyword <range>

Assign or remove groups to particles in the range. Use of the group logic is described in Groups.

remove

Remove the group s from particles within the given range. This does not remove the particles themselves.

slot s

Assign groups in the given range to the slot named s. By default groups will be assigned to slot Default

list <path>

lists summary information about tracking particles. If the path keyword is omitted, the current particle position information is output. If the path keyword is included, then particle path information is output.

trace <name s > i

Creates a location trace (see the trace command) of the particle with ID number i.

zone-based-pp b

Specify that pore-pressures should be retrieved directly from the zone, rather than averaged from the gridpoints. Zone pore pressures must be assigned manually via FISH, using the zone.pp intrinsic.

.. rubric:: zone fluid Keyword Block :class: h2 :name: zonefluidblock

At the time of particle creation the following additional configuration settings may optionally be supplied. They apply to the keywords: line, plane and point.

group s1 <slot s2 >

Assign the created particles to the group s1 and (if supplied) assign that group to slot s2. By default the slot name will be Default.

tail b

When on (the default setting), particles will automatically store a list of coordinates along their path as they move through the grid. If off particles will only keep track of their current position.

tortuosity f

The tortuosity is specified as f, which is defined as the ratio of the straight line path to the actual fluid path through a zone. This factor will be used to multiply track increments calculated from the flow velocity; it defaults to 1 if not given.

[DR: please check that “see —- ” links here land where they should]