Hi Team,

I am new to CADET and trying to implement GRM model Steric Mass isotherm, but I am not getting expected result. I think some error in parameter setting. The details is given below. Please help me how to set up the model. I have taken code from CADET Tutorial Master/05_Simple_chromatographic_process.

Column Volume (mL) = 0.353

Total void =0.592

flow rate (ml/min)= 0.170

col height (m)= 0.050

col radius (cm) = 0.150

Column cross sec area (cm2) = 0.071

velocity (m/s) = 4.01E-04

Particle radius (m)= 3.25E-05

Start IS (mM) = 60.842

Gradient end IS (mM)=288.580

Column Porosity = 0.470

Pore Porosity=0.230

Protein load conc. (mM)= 0.029

Gradient CV = 20.000

Load time (s) = 4232.598

Elution start (s) =7407.137

Gradient end (s)= 9898.902

End time (s)= 9998.902

Gradient slope = 0.091

**Isotherm parameters**

ka= 4.35E-31

nu = 14.000

kd = 1.00E-22

lambda =710.000

sigma= 261.000

||0.000|

||0.358|

**Transport parameters**

Column dispersion (m2/s) =3.90E-07

film diffusion (m/s)=1.00E-05

particle diffusion (m2/s) = 5.50E-12

surface diffusion Dsf (m2/s) = 1.38E-15

My Code here:

```
wash_start = 2009.2
grad_start = 8115.0
t_cycle = 10707.4
lwe_model = get_cadet_template(n_units=3)
# Sections and Switches
lwe_model.root.input.solver.sections.nsec = 3
lwe_model.root.input.solver.sections.section_times = [0.0, wash_start, grad_start, t_cycle]
lwe_model.root.input.model.unit_000.sec_000.const_coeff = [84.105,0.029]
lwe_model.root.input.model.unit_000.sec_001.const_coeff = [84.105,0.0]
lwe_model.root.input.model.unit_000.sec_002.const_coeff = [84.105,0.0]
lwe_model.root.input.model.unit_000.sec_002.lin_coeff = [0.082,0.0]
#set the times that the simulator writes out data for
lwe_model.root.input.solver.user_solution_times = np.linspace(0, t_cycle, int(t_cycle) + 1)
n_comp = 2
# INLET
lwe_model.root.input.model.unit_000.unit_type = 'INLET'
lwe_model.root.input.model.unit_000.ncomp = n_comp
lwe_model.root.input.model.unit_000.inlet_type = 'PIECEWISE_CUBIC_POLY'
# GENERAL_RATE_MODEL
lwe_model.root.input.model.unit_001.unit_type = 'GENERAL_RATE_MODEL'
lwe_model.root.input.model.unit_001.ncomp = n_comp
lwe_model.root.input.model.unit_001.col_length = 0.05
lwe_model.root.input.model.unit_001.cross_section_area = 7.1e-6
lwe_model.root.input.model.unit_001.col_porosity = 0.47
lwe_model.root.input.model.unit_001.par_porosity = 0.23
lwe_model.root.input.model.unit_001.par_radius = 3.25e-5
lwe_model.root.input.model.unit_001.col_dispersion = 3.9e-7
lwe_model.root.input.model.unit_001.film_diffusion = [1.0E-5, 1.0E-7]
lwe_model.root.input.model.unit_001.par_diffusion = [5.5e-12, 5.5e-12]
lwe_model.root.input.model.unit_001.par_surfdiffusion = [1.38e-15, 1.38e-15]
# OUTLET
lwe_model.root.input.model.unit_002.unit_type = 'OUTLET'
lwe_model.root.input.model.unit_002.ncomp = n_comp
## Discretization
set_discretization(lwe_model, n_bound=[1,1])
# Connections
lwe_model.root.input.model.connections.nswitches = 1
lwe_model.root.input.model.connections.switch_000.section = 0
lwe_model.root.input.model.connections.switch_000.connections = [
0, 1, -1, -1, 2.83e-9,
1, 2, -1, -1, 2.83e-9
]
sma_refc0 = lwe_model.root.input.model.unit_000.sec_002.lin_coeff[0] * (t_cycle - grad_start)
lambda_ = 710.0
lwe_model.root.input.model.unit_001.adsorption_model = 'STERIC_MASS_ACTION'
lwe_model.root.input.model.unit_001.adsorption.is_kinetic = 1
lwe_model.root.input.model.unit_001.adsorption.sma_ka = [4.35e-31, 1.0]
lwe_model.root.input.model.unit_001.adsorption.sma_kd = [1.0e-22, 1.0]
lwe_model.root.input.model.unit_001.adsorption.sma_lambda = lambda_
lwe_model.root.input.model.unit_001.adsorption.sma_nu = [0.0, 14.0]
lwe_model.root.input.model.unit_001.adsorption.sma_sigma = [0.0, 261.0]
lwe_model.root.input.model.unit_001.adsorption.sma_refc0 = sma_refc0
lwe_model.root.input.model.unit_001.adsorption.sma_refq = lambda_
lwe_model.root.input.model.unit_001.init_c = [84.105, 0.0]
lwe_model.root.input.model.unit_001.init_q = [lambda_, 0.0]
```