Surface Chemistry Model Reference

表 1. Surface Chemistry Model Reference
Theory	See Chemical Kinetics: Surface Chemistry Surface Chemistry
Provided By	[physics continuum] > Models > Optional Models
Example Node Path	Continua > Physics 1 > Models > Surface Chemistry Porous Media > Porous Phases > Phase 1 > Models > Surface Chemistry
Requires	One of the following combinations of model selections:
	Material: Multi-Component Gas or Multi-Component Liquid Reaction Regime: Reacting Reacting Flow Models: Reacting Species Transport Reacting Species Models: Complex Chemistry or Eddy Break-Up Flow: Segregated Flow or Coupled Flow		Material: Multi-Component Gas or Multi-Component Liquid Reaction Regime: Non-Reacting Flow: Segregated Flow
Activates	Physics Models	After selecting the Surface Chemistry model when the Eddy Break-Up model or Non-Reacting model is selected, the Surface-Gas Interaction model is also selected. See Surface-Gas Interaction Model Reference.
	Model Controls (child nodes)	Surface Mechanism Manager. See Surface Mechanism Manager Right-Click Actions.
	Materials	Specify or review the imported species: gases under the Multi-Component Gas node liquids under the Multi-Component Liquid node site and bulk species under the Surface Chemistry > [SurfaceMechanism] > Solid Composition node See Materials and Methods.
	Interface Inputs	See Interface Settings.
	Boundary Inputs	See Boundary Settings.
	Region Inputs	See Region Settings.
	Phase Inputs	See Porous Phase Settings.
	Solvers	See Porous Mass Phase.
	Field Functions	See Field Functions.

Surface Mechanism Manager Right-Click Actions

New Surface Mechanism: Creates a new SurfaceMechanism with the Reacting Surface subnode, which allows you to create chemical reactions. See Reacting Surface Model Reference.
Right-clicking the SurfaceMechanism node opens the Dependencies dialog that lets you find out which interfaces, regions, or boundaries use the surface mechanism. This option is useful, for example, if you want to delete the SurfaceMechanism node. Before you can delete the SurfaceMechanism node, you must deselect the mechanism from the location where it is applied.
Remove Invalid Surface Mechanism: Removes incorrectly defined surface mechanisms.

Materials and Methods

Specify or review the imported gas or liquid components using the Continua > Physics 1 > Models > Multi-Component Gas/Multi-Component Liquid node. See Defining Species Manually.

Specify the reacting surface using the Models > Surface Chemistry > Surface Mechanism Manager > [Mechanism] > Solid Composition node. See Solid Composition Model Reference.

Site Occupancy: Allows you to specify the number of surface sites, $σ_{j}$ (in Eqn. (3401), Eqn. (3402), and Eqn. (3403)), that each of the adsorbed molecules (species) occupies. Available to set as a material property for each [Site Species] that is specified within the Solid Composition model.
Site Density: Allows you to specify the number of active sites, $ρ_{s i t e}$ (in Eqn. (3595)), that exist on the surface (kmol/m²). Available to set as a material property for the Site Solid Mixture within the Solid Composition model.
Bulk Density: Allows you to specify the number of surface sites on the solid surface that are occupied by bulk species, $N_{b}$ in Eqn. (3393), (kg/m³). Available to set as a material property for each [Bulk Species] that is specified within the Solid Composition model.

Interface Settings

All Except Baffle

For baffle interfaces, you define mechanisms at the baffle interface boundaries.

Surface Mechanism Option

To allow the interface to become a reactive surface, select the Physics Conditions > Surface Mechanism Option sub-node of that interface. Change the Mechanism property to one of the available mechanisms for your simulation. Mechanisms are available only after you import the chemistry definition.

Mechanism	Corresponding Physics Value Nodes
[Surface Mechanism] Defines the interface as a reacting surface.	Surface Initial Bulk Activity Profiles Allows you to set the surface molar fraction for species of the given mechanism on the interface as a scalar array profile, $B_{i}$ in Eqn. (3393). Surface Initial Site Fraction Profiles Allows you to set (as a scalar profile) the fraction of the total number of sites that a given species occupies, $z_{i}$ in Eqn. (3595). This fraction only applies to species of the given mechanism between the interface and the fluid phase. Surface Washcoat Factor Allows you to account for a porous washcoat layer which increases the active surface area of a solid catalyst surface. For example, on interface surfaces that are covered by a porous washcoat, you can specify a surface washcoat factor, $γ_{w}$ in Eqn. (3593) and Eqn. (3594), greater than 1.0. A value of 1.0 represents the surface area before a washcoat is applied.
NONE Defines the interface as a non-reacting surface.

Mechanism

Corresponding Physics Value Nodes

[Surface Mechanism]: Defines the interface as a reacting surface.

Surface Initial Bulk Activity Profiles: Allows you to set the surface molar fraction for species of the given mechanism on the interface as a scalar array profile, $B_{i}$ in Eqn. (3393).
Surface Initial Site Fraction Profiles: Allows you to set (as a scalar profile) the fraction of the total number of sites that a given species occupies, $z_{i}$ in Eqn. (3595). This fraction only applies to species of the given mechanism between the interface and the fluid phase.
Surface Washcoat Factor: Allows you to account for a porous washcoat layer which increases the active surface area of a solid catalyst surface. For example, on interface surfaces that are covered by a porous washcoat, you can specify a surface washcoat factor, $γ_{w}$ in Eqn. (3593) and Eqn. (3594), greater than 1.0. A value of 1.0 represents the surface area before a washcoat is applied.

NONE: Defines the interface as a non-reacting surface.

Boundary Settings

Baffle Interface Boundary

Wall Boundary (for boundaries not associated with an interface)

Surface Mechanism Option

To allow a boundary to become a reactive surface, select the Physics Conditions > Surface Mechanism Option sub-node of that boundary. Change the Mechanism property to one of the available mechanisms for your simulation. Mechanisms are available only after you import the chemistry definition. You can define different mechanisms for boundaries on opposite sides of a baffle interface.

Mechanism	Corresponding Physics Value Nodes
[Surface Mechanism] Defines the boundary as a reacting surface.	Surface Initial Bulk Activity Profiles Allows you to set the surface molar fraction for species of the given mechanism on the interface as a scalar array profile, $B_{i}$ in Eqn. (3393). Surface Initial Site Fraction Profiles Allows you to set (as a scalar profile) the fraction of the total number of sites that a given species occupies, $z_{i}$ in Eqn. (3595). This fraction only applies to species of the given mechanism between the reactive wall and the fluid phase. Surface Washcoat Factor Allows you to account for a porous washcoat layer which increases the active surface area of a solid catalyst surface. For example, on surfaces that are covered by a porous washcoat, you can specify a surface washcoat factor, $γ_{w}$ in Eqn. (3593) and Eqn. (3594), greater than 1.0. A value of 1.0 represents the surface area before a washcoat is applied.
NONE Defines the boundary as a non-reacting surface.

Mechanism

Corresponding Physics Value Nodes

[Surface Mechanism]: Defines the boundary as a reacting surface.

Surface Initial Bulk Activity Profiles: Allows you to set the surface molar fraction for species of the given mechanism on the interface as a scalar array profile, $B_{i}$ in Eqn. (3393).
Surface Initial Site Fraction Profiles: Allows you to set (as a scalar profile) the fraction of the total number of sites that a given species occupies, $z_{i}$ in Eqn. (3595). This fraction only applies to species of the given mechanism between the reactive wall and the fluid phase.
Surface Washcoat Factor: Allows you to account for a porous washcoat layer which increases the active surface area of a solid catalyst surface. For example, on surfaces that are covered by a porous washcoat, you can specify a surface washcoat factor, $γ_{w}$ in Eqn. (3593) and Eqn. (3594), greater than 1.0. A value of 1.0 represents the surface area before a washcoat is applied.

NONE: Defines the boundary as a non-reacting surface.

Region Settings

Porous

Surface Mechanism Option

To allow the internal surfaces within a porous region to become reactive surfaces, select the Physics Conditions > Surface Mechanism Option sub-node of that porous region. Change the Mechanism property to one of the available mechanisms for your simulation. Mechanisms are available only after you import the chemistry definition.

Mechanism	Corresponding Physics Value Nodes
[Surface Mechanism] Defines the porous region as a reacting surface.	Area to Volume Ratio Specifies the surface area of the reacting/catalytic solid per unit volume. Surface Initial Bulk Activity Profiles The Surface Initial Bulk Activity Profiles > [Bulk] Solid Mixture Activity node allows you to set the surface molar fraction for species of the given mechanism on the reactive region as a scalar array profile. Surface Initial Site Fraction Profiles The Surface Initial Site Fraction Profiles > [Site] Solid Mixture Fraction node allows you to set (as a scalar profile) the fraction of the total number of sites that a given species occupies. This fraction only applies to species of the given mechanism on the interface between the reactive region and the fluid phase.
NONE Defines the porous region as non-reacting.

Mechanism

Corresponding Physics Value Nodes

[Surface Mechanism]: Defines the porous region as a reacting surface.

Area to Volume Ratio: Specifies the surface area of the reacting/catalytic solid per unit volume.
Surface Initial Bulk Activity Profiles: The Surface Initial Bulk Activity Profiles > [Bulk] Solid Mixture Activity node allows you to set the surface molar fraction for species of the given mechanism on the reactive region as a scalar array profile.
Surface Initial Site Fraction Profiles: The Surface Initial Site Fraction Profiles > [Site] Solid Mixture Fraction node allows you to set (as a scalar profile) the fraction of the total number of sites that a given species occupies. This fraction only applies to species of the given mechanism on the interface between the reactive region and the fluid phase.

NONE: Defines the porous region as non-reacting.

Field Functions

Surface Bulk Fraction of [Species]
Surface Bulk Growth Rate of [Species]
Surface Bulk Source of [Species]
Surface Chemistry Energy Source
Surface Site Fraction of [Species]: $Z_{S_{i}, n}$ in Eqn. (3395).
Surface Site Source of [Species]