Mohsen Najafi

It appears that you are experiencing difficulties getting the Arrhenius reaction rate model to function properly in ANSYS Fluent. There might be several causes for this. Here are a few things to look into:

1. Check that the reaction rate is appropriately configured in the Reaction panel of the Species Model tab. You must supply the Arrhenius parameters (activation energy and pre-exponential factor) as well as the temperature range in which they are valid.

2. Check that the flow temperature is within the valid range for the Arrhenius parameters. The response rate may not be well-defined if the temperature is too high or too low.

3. Check that the reactant and product terms for the reaction are correctly set up. If they are not properly configured, the response may not occur.

4. Check that the correct species have been given as reactants and products in the reaction. In the Species panel of the Species Model tab, ensure that the species are defined and appropriately titled.

5. Check that you have the correct units for the Arrhenius parameters. The activation energy should be measured in Joules/mol, and the pre-exponential factor should be measured in m3/(mol*s).

The finite rate model and the eddy dissipation model (EDM) are two distinct techniques to describe chemical reactions in a flow simulation in ANSYS Fluent.

The finite rate model is based on the idea that chemical reactions occur at a limited rate governed by reactant concentration and temperature. A rate coefficient, which can be stated as a function of temperature, determines the rate of the reaction. The finite rate model is more accurate than the EDM in general, although it is more computationally expensive to solve.

The EDM, on the other hand, is based on the premise that chemical reactions occur via energy exchange between the fluid and the reaction products. An eddy dissipation rate, which is related to the turbulent kinetic energy of the flow, determines the rate of the response. The EDM is less accurate than the finite rate model in general, but it is faster to solve.

The primary distinction between the finite rate model and the EDM is how they simulate chemical reactions: the finite rate model employs a rate coefficient, whereas the EDM employs an eddy dissipation rate. The finite rate model is more accurate in general, while the EDM is faster to solve.

I hope these recommendations are useful! Please let me know if you have any more queries.

n ANSYS Fluent, "Finite Rate" and "Eddy Rate" are two different models that can be used to model chemical reactions. The main difference between the two is the way they calculate the reaction rates.

Finite Rate: The finite rate model calculates the reaction rate based on the actual chemical reactions taking place in the fluid. It considers the chemical kinetics of the reactions and the local thermodynamic conditions. This model is more accurate but requires more computational resources and detailed information about the chemical reactions.

Eddy Rate: The eddy rate model calculates the reaction rate based on the mixing of the fluid. It assumes that the reactions are controlled by the mixing of the fluid and not by the actual chemical kinetics. This model is less accurate but requires less computational resources and detailed information about the chemical reactions.

Another difference between the two is that the finite rate model is more suited for high-temperature reactions, whereas the eddy rate model is more suited for low-temperature reactions.

In practice, the choice of which model to use depends on the specific situation. The finite rate model is generally used when more accurate results are needed, while the eddy rate model is used when computational resources are limited.