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What is the velocity model used in the fds fire spread process. Is it the level set and the rothermel model |
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There are four options for level set described in the User's Guide. |
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Thank you very much for your answer,but I still don't quite understand.What is the model used for fire spread rate in FDS?And regarding Chapter 17 of the user manual,which includes the Lagrangian Particle Model,Boundary Fuel Model,and Level Set Model,are all three models used in the simulation process,or are these three models different speed models? |
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These are different models. The particle and boundary approaches attempt to model fire spread by solving detailed heat transfer and solid thermal decomposition. The particle approach generally requires a fine enough gas-phase grid to resolve the vertical extent of the fuel layer. The boundary model treats the fuel layer as a boundary condition. The level set model uses simplified algebraic expressions to obtain a spread rate based on fuel properties, topography, and wind, without modeling detailed heat transfer and solid thermal decomposition. The default for this in FDS is the Rothermel model. Examine the CSIRO grass fire validation cases to see how each approach can be implemented. |
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Thank you very much for your patient explanation.Based on your answer,can I understand that all three models are needed when simulating fire spread,and in FDS,the fire spread rate model is only the Level Set-Rothermel model?I'm currently not clear about which fire spread model is specifically used.
…---Original---
From: "Eric ***@***.***>
Date: Sat, Jan 11, 2025 18:19 PM
To: ***@***.***>;
Cc: ***@***.******@***.***>;
Subject: Re: [firemodels/fds] Is the FDS fire spread velocity model optional(Discussion #14029)
These are different models.
The particle and boundary approaches attempt to model fire spread by solving detailed heat transfer and solid thermal decomposition. The particle approach generally requires a fine enough gas-phase grid to resolve the vertical extent of the fuel layer. The boundary model treats the fuel layer as a boundary condition.
The level set model uses simplified algebraic expressions to obtain a spread rate based on fuel properties, topography, and wind, without modeling detailed heat transfer and solid thermal decomposition. The default for this in FDS is the Rothermel model.
Examine the CSIRO grass fire validation cases to see how each approach can be implemented.
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All three approaches can be used to predict a fire spread rate. They are typically used separately, choosing one approach based on grid resolution and information available. See the 'CSIRO' validation cases to see how the approaches can be substituted. In some instances they may be combined, such as when the surface fuel cannot be well resolved but canopy fuel can be. See the 'crown fire' validation cases for an example of this. |
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Thank you again for your patient answer.❤️
…---Original---
From: "Eric ***@***.***>
Date: Sat, Jan 11, 2025 18:39 PM
To: ***@***.***>;
Cc: ***@***.******@***.***>;
Subject: Re: [firemodels/fds] Is the FDS fire spread velocity model optional(Discussion #14029)
All three approaches can be used to predict a fire spread rate. They are typically used separately, choosing one approach based on grid resolution and information available. See the 'CSIRO' validation cases to see how the approaches can be substituted. In some instances they may be combined, such as when the surface fuel cannot be well resolved but canopy fuel can be. See the 'crown fire' validation cases for an example of this.
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Reply to this email directly, view it on GitHub, or unsubscribe.
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There are four options for level set described in the User's Guide.