The Surface-to-Surface (S2S) and Discrete Ordinates (DO) models in Ansys Fluent are both used for simulating radiative heat transfer, but they have different approaches and applications:
Surface-to-Surface (S2S) Model
- Assumptions: Assumes that the medium between surfaces does not participate in radiation (i.e., no absorption, emission, or scattering by the medium).
- Application: Best suited for enclosures with gray-diffuse surfaces where radiation exchange is significant.
- Method: Uses view factors to calculate the radiative exchange between surfaces. The view factor depends on the size, separation distance, and orientation of the surfaces1.
- Computational Cost: Can be computationally expensive due to the need to calculate view factors for all surface pairs, but clustering techniques can reduce this cost1.
Discrete Ordinates (DO) Model
- Assumptions: Solves the radiative transfer equation (RTE) for a finite number of discrete solid angles, allowing for absorption, emission, and scattering by the medium.
- Application: Suitable for complex geometries and participating media where the medium itself interacts with radiation.
- Method: Transforms the RTE into a set of transport equations for radiation intensity in different directions. This model can handle non-gray radiation by dividing the spectrum into wavelength bands2.
- Computational Cost: Generally more flexible and can be more computationally intensive due to solving multiple transport equations, but it provides a more detailed analysis of radiative heat transfer2.
In summary, the S2S model is ideal for scenarios where the medium does not interact with radiation, focusing on surface interactions, while the DO model is more versatile, handling interactions within the medium and complex geometries.
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