Hello Dear MS users,
I am trying to calculate viscosity of a polymer solution. Accordingly, after model construction and doing main simulation I applied Forcite->Shear task. But i did not know what the best way to choice SHEAR RATE is!!! In order to solve this problem i calculate Rotational time correlation function from Forcite analysis to find relaxation time. In order to that I calculate Rotational time correlation function for polymer chain in the solution due to its more complexity compared to solvent molecule. Then i tried to fit stretched exponential Kohlrausch−Williams−Watts (KWW) [y=A exp(-(t/t0)^B)] on the second Legendre polynomial (M2).
I tried a lot for fitting on all data but i could not. But according to reference
"THE JOURNAL OF CHEMICAL PHYSICS 128, 184905 2008"
I found that only part of the data could fit on stretched exponential curve. Accordingly, i calculated B=0.89 and finally t0=7.6*105 ps. I calculated shear rate of a mixture according to Question Title “How to calculate the viscosity” (shear rate=1/t0). The calculated shear rate is 1.3*10-5. This shear rate is too short. I really do not know the correctness of my applied method. Generally how the appropriate shear rate can be obtained? I will be thankful if guide me.
Best Regards
Sousa
I am trying to calculate viscosity of a polymer solution. Accordingly, after model construction and doing main simulation I applied Forcite->Shear task. But i did not know what the best way to choice SHEAR RATE is!!! In order to solve this problem i calculate Rotational time correlation function from Forcite analysis to find relaxation time. In order to that I calculate Rotational time correlation function for polymer chain in the solution due to its more complexity compared to solvent molecule. Then i tried to fit stretched exponential Kohlrausch−Williams−Watts (KWW) [y=A exp(-(t/t0)^B)] on the second Legendre polynomial (M2).
I tried a lot for fitting on all data but i could not. But according to reference
"THE JOURNAL OF CHEMICAL PHYSICS 128, 184905 2008"
I found that only part of the data could fit on stretched exponential curve. Accordingly, i calculated B=0.89 and finally t0=7.6*105 ps. I calculated shear rate of a mixture according to Question Title “How to calculate the viscosity” (shear rate=1/t0). The calculated shear rate is 1.3*10-5. This shear rate is too short. I really do not know the correctness of my applied method. Generally how the appropriate shear rate can be obtained? I will be thankful if guide me.
Best Regards
Sousa
