[post_grad]

Hi everyone,
I am currently doing some research on gas-solid fluidization and I am tasked with simulating the fluidization of Geldart B particles with the bubbling EMMS drag model.
I have written the UDF as per the paper: http://dx.doi.org/10.1155/2016/8256816

It includes 7 equations to find different parameters and finally calculate the drag coefficient. I successfully compiled the code but when I run the simulation, I am getting a floating point error. I tried to find the source of the error and I think it has something to do with the calculation of the void fraction of gas in the cells. For some reason, I am getting 1 for the voidage of gas in the cells. I think it should be below 1.

I have attached my code for reference.
Any help would be greatly appreciated.