Reaction i

Index Reaction i Ver: 0

DESCRIPTION

This menu allows to set the parameters of a chemical reaction. OPTIONS

-3 Check mass balance

Computes the mass balance. A non vanishing residual reflects an incorrect mass balance. Note that a non vanishing residual will not yield an error message.

-2 Domain of reaction

Allows to define the (volume) domain where the chemical reaction takes place. By default, the domain of the reaction is defined over the entire mesh. Restriction to (volume) sub-parts is perfectly valid.

-1 Upper level menu

0 Reverse reaction

Gives the user the access to the reverse part of a reversible reaction for introduction of the reaction-dependent parameters. Available for reversible reactions only.
As an alternative to the definition of a reversible reaction, the user may define two irreversible reactions : the forward and the reverse. In this case, however, two (!) reactions are needed. This requires more input while consuming two places in the list of chemical reactions.

1 Modification of equation name

Allows the user to name a chemical equation. The default name is 'forward #i', i being the index of the reaction. For the reverse side : reverse #i'.

2 Rate 'constant'

Allows the user to define/modify the data relative to the rate constant (see rate_constant).

3' Switch to real orders

When activated, this option forces the orders of reaction to be treated as real numbers. If the orders of reaction are real numbers, then the program will use the signed modulus of the mole concentration when evaluating the molar rate. By default, orders of reaction are considered integer quantities.

3" Switch to integer orders

Complementary option to option 3'. Please note that if the orders are integer quantities, a negative mole concentration will not cause a floating point error : the operation -2.d0 is performed by a series of multiplications, whereas the operation -2.d0**3.d0 is performed via logarithms. If the orders are real or double precision, then a purely negative mole concentration will cause a floating point error.

3+i Modification of power of mole concentration of species with index i.

Defines/modifies the set of exponential powers. Orders of reaction are initialized based on the stoichiometric coefficients of the reactant species. Orders of reaction for the product species are defaulted to zero. Please note that the exponential orders are not necessarily the stoichiometric coefficients of the species.
In view of the Newton-Raphson implementation of the solution procedure, the system may be very sensitive to small perturbations. In particular, the use of orders of reaction between 0 and 1 should be avoided, as it may render the resulting Jacobian matrix stiff. This behavior is similar to that of power-law fluids with low power-law indices for which a Picard scheme is recommended, thus dropping the derivatives of the power-law functions with respect to nodal unknowns.
Evolution is not permitted.

SEE ALSO

rate constant
Chemically Reacting Flows (UM)
Defining Chemical Reactions (UM)

-3	Check mass balance
	Computes the mass balance. A non vanishing residual reflects an incorrect mass balance. Note that a non vanishing residual will not yield an error message.
-2	Domain of reaction
	Allows to define the (volume) domain where the chemical reaction takes place. By default, the domain of the reaction is defined over the entire mesh. Restriction to (volume) sub-parts is perfectly valid.
-1	Upper level menu
0	Reverse reaction
	Gives the user the access to the reverse part of a reversible reaction for introduction of the reaction-dependent parameters. Available for reversible reactions only. As an alternative to the definition of a reversible reaction, the user may define two irreversible reactions : the forward and the reverse. In this case, however, two (!) reactions are needed. This requires more input while consuming two places in the list of chemical reactions.
1	Modification of equation name
	Allows the user to name a chemical equation. The default name is 'forward #i', i being the index of the reaction. For the reverse side : reverse #i'.
2	Rate 'constant'
	Allows the user to define/modify the data relative to the rate constant (see rate_constant).
3'	Switch to real orders
	When activated, this option forces the orders of reaction to be treated as real numbers. If the orders of reaction are real numbers, then the program will use the signed modulus of the mole concentration when evaluating the molar rate. By default, orders of reaction are considered integer quantities.
3"	Switch to integer orders
	Complementary option to option 3'. Please note that if the orders are integer quantities, a negative mole concentration will not cause a floating point error : the operation -2.d0 is performed by a series of multiplications, whereas the operation -2.d0**3.d0 is performed via logarithms. If the orders are real or double precision, then a purely negative mole concentration will cause a floating point error.
3+i	Modification of power of mole concentration of species with index i.
	Defines/modifies the set of exponential powers. Orders of reaction are initialized based on the stoichiometric coefficients of the reactant species. Orders of reaction for the product species are defaulted to zero. Please note that the exponential orders are not necessarily the stoichiometric coefficients of the species. In view of the Newton-Raphson implementation of the solution procedure, the system may be very sensitive to small perturbations. In particular, the use of orders of reaction between 0 and 1 should be avoided, as it may render the resulting Jacobian matrix stiff. This behavior is similar to that of power-law fluids with low power-law indices for which a Picard scheme is recommended, thus dropping the derivatives of the power-law functions with respect to nodal unknowns. Evolution is not permitted.