Hi there,

I am having a simple box geometry (2D). I am using a reduced CHEMKIN mechanism for n-heptane for the combustion purpose. The initial conditions are as follows.

Initial mixture mass concentration: 

nC7H16: 0.028

N2: 0.745

O2: 0.227

Initial temperature: 1000 K

Initial Pressure: 42 bar

There is a uniform mixture of air and fuel in the 5mm x 10mm box. I am using ANSYS Fluent to solve the combustion problem. 

Model used: Species Model

Reaction: Volumetric with Eddy dissipation concept.

When I run the unsteady simulation, the ignition always starts from the wall and it propagates to the middle of the box. It takes significant time to reach to the centre. For almost 7 milliseconds, there is no ignition at the middle of the box. 

Can anybody suggest me why is this happening ? If the mixture is uniform throughout, it should ignite at the middle also. Please help me with the problem. 

The temperature plot is attached herewith.

Thanks a lot in advance.

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