-
Notifications
You must be signed in to change notification settings - Fork 24
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
- Loading branch information
Showing
810 changed files
with
2,369 additions
and
49 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,30 @@ | ||
# Stability and critical points | ||
|
||
The implementation of critical points in $\text{FeO}_\text{s}$ follows the algorithm by [Michelsen and Mollerup](https://tie-tech.com/new-book-release/). A necessary condition for stability is the positive-definiteness of the quadratic form ([Heidemann and Khalil 1980](https://doi.org/10.1002/aic.690260510)) | ||
|
||
$$\sum_{ij}\left(\frac{\partial^2 A}{\partial N_i\partial N_j}\right)_{T,V}\Delta N_i\Delta N_j$$ | ||
|
||
The **spinodal** or limit of stability consists of the points for which the quadratic form is positive semi-definite. Following Michelsen and Mollerup, the matrix $M$ can be defined as | ||
|
||
$$M_{ij}=\sqrt{z_iz_j}\left(\frac{\partial^2\beta A}{\partial N_i\partial N_j}\right)$$ | ||
|
||
with the molar compositon $z_i$. Further, the variable $s$ is introduced that acts on the mole numbers $N_i$ via | ||
|
||
$$N_i=z_i+su_i\sqrt{z_i}$$ | ||
|
||
with $u_i$ the elements of the eigenvector of $M$ corresponding to the smallest eigenvector $\lambda_1$. Then, the limit of stability can be expressed as | ||
|
||
$$c_1=\left.\frac{\partial^2\beta A}{\partial s^2}\right|_{s=0}=\sum_{ij}u_iu_jM_{ij}=\lambda_1=0$$ | ||
|
||
A **critical point** is defined as a stable point on the limit of stability. This leads to the second criticality condition | ||
|
||
$$c_2=\left.\frac{\partial^3\beta A}{\partial s^3}\right|_{s=0}=0$$ | ||
|
||
The derivatives of the Helmholtz energy can be calculated efficiently in a single evaluation using [generalized hyper-dual numbers](https://doi.org/10.3389/fceng.2021.758090). The following methods of `State` are available to determine spinodal or critical points for different specifications: | ||
|
||
||specified|unkonwns|equations| | ||
|-|-|-|-| | ||
|`spinodal`|$T,N_i$|$\rho$|$c_1(T,\rho,N_i)=0$| | ||
|`critical_point`|$N_i$|$T,\rho$|$c_1(T,\rho,N_i)=0$<br/>$c_2(T,\rho,N_i)=0$| | ||
|`critical_point_binary_t`|$T$|$\rho_1,\rho_2$|$c_1(T,\rho_1,\rho_2)=0$<br/>$c_2(T,\rho_1,\rho_2)=0$| | ||
|`critical_point_binary_p`|$p$|$T,\rho_1,\rho_2$|$c_1(T,\rho_1,\rho_2)=0$<br/>$c_2(T,\rho_1,\rho_2)=0$<br/>$p(T,\rho_1,\rho_2)=p$| |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.