4 THE R1D RECORDS

The R1D input defines the physical properties and discretization of the local subsystems. These are one-dimensional units which may be attached to any global block within the system. They may be used to simulate the second porosity of a fractured media or they may be used to broaden the boundaries of the global system at minimal expense. This particular capability of the SWIFT II code is described by Reeves et al. [1986a], Sections 2.3, 5.6 and 7.1.3.

If KSLVD = 0 (READ M-3), then all R1D input should be skipped.

4.1 PHYSICAL AND DISCRETIZATION PARAMETERS

READ R1D-1 (E10.0) Rock Compressibility.

LIST: CRD CRD Compressibility of the rock within the local subsystems, psi^-1 (Pa^-1). READ R1D-2 (LIST 1: 7E10.0; LIST 2: 2I5,3E10.0; LIST 3: 7E10.0) Properties Dependent upon Local Rock Type.

A set of three records is read for each local rock type assuming a natural ordering of the rock types, i.e., IR = 1,2,..., NRTD.

LIST 1: DMEFD, DMFD1, PHID, AKSD, ALPD, UKTD, CPRKD
DMEFD Diffusivity, ft²/d (m²/s).

DMFD1 Coefficient of thermal increase in diffusivity,

EF^-1 (EC^-1).

PHID Porosity.

AKSD Permeability, ft/d (m/s).

ALPD Dispersivity, ft (m).

UKTD Thermal conductivity, Btu/ft-d-EF (J/m-s-EC).

CPRKD Heat capacity, Btu/ft³-EF (J/m³-EC).

LIST 2: KGDP, KGRD, SAD, DSD, DSDO
KGDP Geometry control.
0 - Spherical structural units.

1 - Prismatic structural units.

KGRD Local grid control.
0 - Node-to-node increment values are input.

1 - Single-mesh generation.

2 - Double-mesh generation.

SAD Length of prismatic units or radius of spherical units. DSD Increment specification at interface of local subsystem with global system, ft (m). DSDO Increment specification at the outer extremity of local subsystem, ft (m). For single-mesh generation, the three parameters NSD (READ R0D-2), SAD and DSD are used to generate nodal positions for the local subsystem. See Figure 4-1a. For double-mesh generation, the four parameters, NSD,

SAD, DSD and DSDO are used to generate nodal positions. See Figure 4-1b.

Reference: Reeves et al. [1986a], Section 7.1.3.

If KGRD … 0 skip the following list.

LIST 3: DS(I), I=1,NSD-1

DS Node-to-node increment values where I = 1 denotes the outermost increment and I = NSD-1 denotes the increment at the system interface, ft (m).

Figure 4-1. Mesh generation for the local subsystems.

Fig 4-1

4.2 INITIAL AND OUTER BOUNDARY CONDITIONS FOR THE PRIMARY VARIABLES

In this section boundary conditions for the outer extremity of the local subsystem and initial conditions for the local subsystem are prescribed for the primary variables as a function of local rock type. The boundary condition at the local/global interface is not under user control since it is always matched implicitly to the value of the corresponding global variable.

Enter as many records as necessary to define all initial and boundary conditions. Terminate the input here with a blank record. Even if no boundary specifications are desired, a blank record must still be used.

READ R1D-3 (LIST 1: 5I5; LIST 2: 3E10.0)

LIST 1: IR, KBC, KPB, KTPB, KSWB IR Local rock type.

KBC Boundary-condition control

0 - No-flow (no-flux) conditions are invoked for all primary variables, P´, T´ and C´.

1 - Dirichlet conditions are taken for all primary variables.

2 - Dirichlet conditions are used for the variables T´ and a no-flux condition is used for P´ and C´.

3 - Dirichlet conditions are used for the variables C´ and a no-flux condition is used for T´. Note: A fluid flux is calculated due to density changes.

KPB Conditional pressure control. Operative only for KBC > 0. See Figure 4-2 for a pictorial definition of the available options. 0 - Both boundary and initial conditions are fixed at the global-block value.

1 - The boundary condition is set at the value prescribed in List 2, and the initial condition is fixed at the global-block value.

2 - The boundary condition is set at the value prescribed in List 2, and the initial condition is fixed at the boundary-condition value.

3 - The boundary condition is set at the value prescribed in List 2, and the initial condition varies directly from the Dirichlet condition at the outer extremity to the global-block value at the system interface.

KTPB Temperature control. Operative for KBC = 1 and KBC = 2 only. The options here are the same as that of KPB (see Figure 4-2).

KSWB Brine control. Operative for KBC = 1 and KBC = 3 only. The options here are the same as that of KPB (see Figure 4-2).

LIST 2: PBD, TPBD, SWBD PBD Specified boundary value for pressure, psi (Pa).

TPBD Specified boundary value for temperature, EF (EC).

SWBD Specified boundary value for brine concentration, mass fraction.

Figure 4-2. Initial/boundary conditions for the primary variables within the local subsystems.
Fig 4-2

4.3 DISTRIBUTION COEFFICIENTS

If there are no radioactive components, i.e., NCP = 0 (READ M-3), skip this input set. Otherwise read one data set for each rock type.

READ R1D-4 (7E10.0)

LIST: DISD(IC), IC = 1,NCP
DISD Distribution coefficient in ft³/lb (m³/kg) for local rock-type IR and component IC.

4.4 RADIONUCLIDE BOUNDARY CONDITIONS

Radionuclide boundary conditions are not under the direct control of the analyst. They are set internally to be consistent with the condition used for the flow. Thus, for a constant-pressure condition, a convective flux condition is set on the radionuclide transport. For a no-flow condition, of course, a no-flux condition is used for the radionuclide equation.

4.5 DUAL POROSITY BLOCK MODIFICATIONS

Follow the data listed below with a blank record. If no modifications, a blank record is still required.

READ R1D-5 (LIST 1; 6I5; LIST 2: E10.0)

LIST 1: I1, I2, J1, J2, K1, K2 I1, I2 Lower and upper limits, inclusive on the I index of the global blocks to be modified.

J1, J2 (Similar definition for the J index.)

K1, K2 (Similar definition for the K index.)

LIST 2: FAMD FAMD If positive, this is the factor by which the cross-sectional area within the defined region are to be multiplied. If negative, the absolute value of FAMD will be used within the region to be modified.