# zone face apply command

Syntax

zone face apply keyword <range>

Primary keywords:

This command is used to apply boundary conditions at surface faces of the model. To apply conditions to zones rather than at faces, see the zone apply command. To apply conditions at individual gridpoints, see the zone gridpoint fix command.

The user must specify the condition type, the numerical value or values associated with it, optional modifiers that may vary the value over time and space, and an optional range over which the boundary condition is to be applied. If no range is specified, then the command applies to the entire model.

To remove a boundary created with this command, see zone face apply-remove.

After the supplied condition’s value(s), an optional modifier keyword can be used to modulate the supplied value. These are marked <[faceapplyblock]> in the commands, with definitions found in the “Keyword Block” section at the end of this topic.

Note that some apply conditions (like velocity) are actually applied to the gridpoints attached to all the faces in the range. This could cause a conflict between gridpoints that are connected to multiple faces with conflicting apply conditions specified. Whenever possible, FLAC3D will attempt to satisfy all conditions — including automatically adjusting the gridpoint local axes system to accomodate the constraints. If this is not possible, however, the velocity condition applied last will dominate.

Note

Occasionally you may want to apply a condition to a set of internal faces. To do this, we recommend temporarily nulling out one side with the zone cmodel assign command, applying the condition, and then restoring the zones to their original constitutive model. This will allow the apply logic to select the appropriate orientation when necessary — for applying stress boundary conditions, for example.

acceleration v

Vector of the acceleration components applied in the global coordinate axes (available only if model configure dynamic has been specified). This is a gridpoint based condition.

acceleration-dip f

Acceleration component applied in the dip direction of the local gridpoint axes — available only if model configure dynamic has been specified (see Local Axes System below). This is a gridpoint based condition.

acceleration-local v

Vector of the acceleration components applied in the local gridpoint axes — available only if model configure dynamic has been specified (see Local Axes System below). This is a gridpoint based condition.

acceleration-normal f

Acceleration component applied in the normal direction of the local gridpoint axes — available only if model configure dynamic has been specified (see Local Axes System below). This is a gridpoint based condition.

acceleration-strike f

Acceleration component applied in the strike direction of the local gridpoint axes — available only if model configure dynamic has been specified (see Local Axes System below). This is a gridpoint based condition.

acceleration-x f

x-component of acceleration applied at a gridpoint — available only if model configure dynamic has been specified. This is a gridpoint based condition.

acceleration-y f

y-component of acceleration applied at a gridpoint — available only if model configure dynamic has been specified. This is a gridpoint based condition.

acceleration-z f

z-component of acceleration applied at a gridpoint — available only if model configure dynamic has been specified. This is a gridpoint based condition.

convection f1 f2

A thermal convective boundary condition is applied over the range of faces specified (available only if model configure thermal has been specified). f1 is the temperature Te of the medium to which convection occurs. f2 is the convective heat transfer coefficient h (e.g., in W/m2◦ C).

discharge f

Fluid flux f is the component of the specific discharge vector (e.g., in m/s) applied normal to the boundary.

flux f

A flux is applied over the range of faces specified (available only if model configure thermal has been specified). f is the initial flux (e.g., in W/m2). This command is used to specify a constant flux into (f > 0) or out of (f < 0) a thermal boundary of the grid. Decay of the flux can be represented by applying a time-varying modifier available in <[faceapplyblock]>.

leakage f1 f2

f1 is the pore pressure in the leaky layer.

f2 is the leakage coefficient, h (e.g., in m3/N sec).

See this equation in Fluid Flow Boundary and Initial Conditions in FLAC3D for the formula for a leaky boundary condition. A leaky condition is applied over the range of faces specified. The history keyword is not active for leakage.

pore-pressure f

Applies a specific pore-pressure value (available only if model configure fluid has been specified). This is a gridpoint based condition.

quiet

Quiet (viscous) boundary applied in all direction of the local gridpoint axes — available only if model configure dynamic has been specified (see Local Axes System below).

quiet-dip

Quiet (viscous) boundary applied in the dip direction of the local gridpoint axes — available only if model configure dynamic has been specified (see Local Axes System below).

quiet-normal

Quiet (viscous) boundary applied in the normal direction of the local gridpoint axes — available only if model configure dynamic has been specified (see Local Axes System below).

quiet-strike

Quiet (viscous) boundary applied in the strike direction of the local gridpoint axes — available only if model configure dynamic has been specified (see Local Axes System below).

reaction

Vector of all components of reaction force at a gridpoint Reaction forces will only be applied in directions that are currently fixed, and those fixity conditions will be removed. This is a gridpoint based condition.

reaction-dip

Reaction force in the dip direction of the local gridpoint axes Reaction forces will only be applied in directions that are currently fixed, and those fixity conditions will be removed. This is a gridpoint based condition.

reaction-local

Apply a reaction force in all components of the local coordinate system (see Local Axes System below). Reaction forces will only be applied in directions that are currently fixed, and those fixity conditions will be removed. This is a gridpoint based condition.

reaction-normal

Reaction force in the normal direction of the local gridpoint axes (see Local Axes System below). Reaction forces will only be applied in directions that are currently fixed, and those fixity conditions will be removed. This is a gridpoint based condition.

reaction-strike

Reaction force in the strike direction of the local gridpoint axes (see Local Axes System below). Reaction forces will only be applied in directions that are currently fixed, and those fixity conditions will be removed. This is a gridpoint based condition.

reaction-x

x-component of reaction force at a gridpoint Reaction forces will only be applied in directions that are currently fixed, and those fixity conditions will be removed. This is a gridpoint based condition.

reaction-y

y-component of reaction force at a gridpoint Reaction forces will only be applied in directions that are currently fixed, and those fixity conditions will be removed. This is a gridpoint based condition.

reaction-z

z-component of reaction force at a gridpoint Reaction forces will only be applied in directions that are currently fixed, and those fixity conditions will be removed. This is a gridpoint based condition.

stress-dip f

Stress component applied in the dip direction of the local face axes (see Local Axes System below).

stress-normal f

Stress component applied in the normal direction of the local face axes (see Local Axes System below).

stress-strike f

Stress component applied in the strike direction of the local face axes (see Local Axes System below).

stress-xx f

xx-component of the stress tensor applied at a face

stress-xy f

xy-component of the stress tensor applied at a face

stress-xz f

xz-component of the stress tensor applied at a face

stress-yy f \

yy-component of the stress tensor applied at a face

stress-yz f

xz-component of the stress tensor applied at a face

stress-zz f

zz-component of the stress tensor applied at a face

temperature f

Fixes and applies a specific temperature value to the gridpoint (available only if model configure thermal has been specified). This is a gridpoint based condition.

velocity v

Vector of all velocity components in the global coordinate axes. This is a gridpoint based condition.

velocity-dip f

Velocity component applied in the dip direction of the local gridpoint axes (see Local Axes System below). This is a gridpoint based condition.

velocity-local v

Vector of all velocity components in the local coordinate axes (see Local Axes System below). This is a gridpoint based condition.

velocity-normal f

Velocity component applied in the normal direction of the local gridpoint axes (see Local Axes System below). This is a gridpoint based condition.

velocity-strike f

Velocity component applied in the strike direction of the local gridpoint axes (see Local Axes System below). This is a gridpoint based condition.

velocity-x f

x-component of velocity applied at a gridpoint This is a gridpoint based condition.

velocity-y f

y-component of velocity applied at a gridpoint This is a gridpoint based condition.

velocity-z f

z-component of velocity applied at a gridpoint This is a gridpoint based condition.

Local Axes System

The local face axes are defined by the normal to the face. The dip, strike, and normal directions form a right-handed coordinate system. Given the normal vector, the other local axes are defined by “$$d$$-axis,” which points downward (i.e., in the negative $$z$$-direction) along the dip-direction, and “$$s$$-axis,” which is horizontal (i.e., lies within the $$xy$$-plane) such that $$d-s-n$$ form a right-handed system as illustrated here.

Figure 1: Local face axes.

zone face apply Keyword Block

The following keywords may be used to modify a supplied value. If the description of the modifier keyword mentions what type of value it may be applied to (e.g. scalar value, vector value, etc.), be sure there is a match between the modifier and the main keyword value. The commands main keywords are: acceleration, acceleration-dip, acceleration-local, acceleration-normal, acceleration-strike, acceleration-x, acceleration-y, acceleration-z, convection, discharge, flux, leakage, pore-pressure, quiet, quiet-dip, quiet-normal, quiet-strike, reaction, reaction-dip, reaction-local, reaction-normal, reaction-strike, reaction-x, reaction-y, reaction-z, stress-dip, stress-normal, stress-strike, stress-xx, stress-xy, stress-xz, stress-yy, stress-yz, stress-zz, temperature, velocity, velocity-dip, velocity-local, velocity-normal, velocity-strike, velocity-x, velocity-y and velocity-z.

fish s

Specify a multiplier that is a FISH function named s. The returned value of this FISH function is multiplied by the base value (including gradient) over all zone faces or gridpoints included in this apply condition. So a return value of 1.0 will apply the base value provided, and a return value of 0.0 will effectively remove it. This function will be called every step. If the apply condition requires a vector value, this function should also return a vector. If the apply condition requires two values, the function should return a vector and the z-component will be ignored.

fish-local s

Specify a multiplier that is a FISH function named s, which is applied separately to each individual zone face or gridpoint affected by this apply condition. This function must take two arguments. For apply conditions that work directly on faces, the first argument is a pointer to the zone and the second argument is an integer from 1 to 6 indicating the face. For apply conditions that work on gridpoints, the first argument is a pointer to the gridpoint and the second argument is not used. This allows an apply condition to vary over time as well as space. The returned value of this FISH function is multiplied by the base value (including gradient) on the specific zone supplied. So a return value of 1.0 will apply the base value provided, and a return value of 0.0 will effectively remove it. This function will be called every step for every zone included in the apply condition. If the apply condition requires a vector value, this function should also return a vector. If the apply condition requires two values, the function should return a vector and the z-component will be ignored.

Apply a gradient to the scalar-value provided. This is not availble if the apply conditions requires two values or a vector value.

servo keyword ...

Use a servo tied to the mechanical convergence ratio to control the magnitude of the applied condition. This can be used to maintain, gradually ramp up, or gradually reduce apply conditions while maintaining a quasi-static response. This controls a factor that is multiplied with the base value supplied. By default the factor will start at 0.001, and will gradually increase to 1.0 as the convergence ratio falls below 2e-3, and decrease if it rises above 1e-2. The following keywords are available to control the servo response:

latency i

The minimum number of steps that must pass since the last servo adjustment before the next one occurs. This can keep the servo from overcontrolling in the initial response to a change in the factor. The default value is 1.

lower-bound f

Set the lower mechanical convergence ratio limit. If the current ratio falls below this limit, the factor will be multiplied by the lower-multiplier. The default limit is 2e-3.

lower-multiplier f

If the current ratio falls below the lower-bound limit, the factor is multiplied by this number. The default is 1.01.

maximum f

The maximum value the factor is allowed to become. The default is 1.0.

minimum f

The minimum value the factor is allowed to become. The default is 0.001.

ramp

Sets the servo into ramp mode. This means that the factor is not allowed to go down, the value will only increase. This is useful to gradually increase an applied condition to it’s full value. See also the reduce keyword.

ratio keyword

Which mechanical convergence ratio is compared against lower-bound and upper-bound. By default this is the current value assigned by the zone ratio command (which is average by default. See the zone ratio command for definitions. The available keywords are:

average

Use the average mechanical force ratio.

maximum

Use the maximum mechanical force ratio.

local

Use the local mechanical force ratio.

reduce

Sets the servo into reduce mode. In this mode the starting value of the factor is 1.0, and the minimum value is set to 0.0. When the current ratio falls below lower-bound the factor is reduced by the upper-multiplier. The factor is never increased. This is useful to gradually decrease an applied condition to zero.

upper-bound f

Set the upper mechanical convergence ratio value. If the current ratio rises above this value, the factor will be multiplier by the upper-multiplier. The default is 1e-2.

upper-multiplier f

If the current ratio rises above the upper-bound, the factor is multiplied by this. The default is 0.975.

system keyword ...

The local coordinate system used by the apply condition may be specified explicitly by the user. By default, this coordinate system is determined auomaticaly. For faces it is determined by the normal direction of the face. For gridpoints it is determined by the average normal vectors of all faces connected to the gridpoint that are a part of this apply condition.

The local coordinate system may be specified in one of two ways, using by either the keyword normal or using the keywords dip and dip-direction together.

normal v

v is the unit normal vector to the plane.

dip f

dip [degrees], f, of the plane measured in the negative z-direction from the global xy-plane.

dip-direction f

dip-direction [degrees], f, of the plane measured in the global xy-plane clockwise from the positive y-axis.

table s <time keyword>

Specify a multiplier that is a table named s. By default the x-axis value is the current step number. The optional time keyword may be used to specify which processes accumulated time-total should be used to provide the x-axis value. The available keywords are:

creep
dynamic
fluid
mechanical
step
thermal
vary v

Apply a linear variation to the scalar-value provided. This is not availble if the apply conditions requires two values or a vector value.

[DR: is location of local axes here ok, or should it be elsewhere? And, is more material needed?