Density
DESCRIPTION
Unless otherwise specified, the fluid density remains constant and its default value is zero.
In the case of a flow problem where the density has been made dependent upon one or more field variables with the help of the PMAT keyword, an average value must be entered.
In the case of gas flow problem, the density varies in function of temperature as described by the perfect gas law.
For all problems except the gas flow problem :
Upper level menu The current value is accepted Modification of density The current value of the density is modified Modification of average density The current value of the average density is modified. This option is presented only when the density has been made dependent upon field variables with the help of the PMAT keyword. Density boundary conditions Allows for setting boundary conditions on the density. This option is presented only when the density has been made dependent upon field variables with the help of the PMAT keyword.
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Upper level menu |
| The current values are accepted | |
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1
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Modification of P0 |
| Operating pressure in reactor. Default value is 101325 Pa, i.e. the atmospheric pressure. | |
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2
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Modification of Mw |
| Molecular weight of the gas. Default value is 1. | |
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3
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Modification of Rg |
| Rg is the ideal gas constant. Default value is 8.3143. |
For all other problem, a constant fluid density may interact with several non-linearities :
When convergence
difficulties are encountered, an evolution scheme should be considered
with increasing r0. This is not possible, however, in the case of the gas
flow problem where the evolution scheme has to be applied to other variables
such as inflow flux, boundary temperature, etc.
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| r0 |
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| r0init |
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