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Found 7 results

  1. Hi GWB team, I'm attempting to react a specified volume of fluid with a certain chemistry through a mass of olivine with a certain grain size over a year. I am able to do this using X1t, such that olivine dissolves into the fluid as the fluid migrates through. However, I'd like to essentially add more olivine as the initial olivine is dissolved away. Is there a way to do this? I played around with doing this in React - like the "Flush.rea" tutorial - however that does not let you specify grain size. Another example is this quartz aquifer one: https://academy.gwb.com/dissolution.php which is what I’m sort of aiming to do but I’d like to specify grain size of the aquifer. As part of this experiment, I'm hoping to keep track of total olivine dissolved, total fluid passing through the system, and chemistry of that fluid. I've attached an initial script and database to give an idea of what I'm trying to do. Thanks for all the help! thermo.presaltnov2017.dat forsterite_large_v1.x1t
  2. Just finished the 2020 workshop, and I’m practicing the users’ guide example “weathering.x1t.” I’m trying to simulate the weathering in a soil profile under various precipitation (rainfall) conditions. Here is my conceptual model: (1) The soil profile is 1cm * 1cm * 300cm. (2) The porosity of the soil profile is 45% and the water content is 25%. (3) The water infiltration rate is 0.3m/yr. (4) The annual rainfall is 600 mm/year. (5) The simulation time is 20000 years. (6) temperature is 13℃ So far, the software settings are like the attached file. I am not sure whether the software settings match my conceptual model mentioned above. Also, what does it mean if the “reactant times” was set to be “1” in this software settings? Thanks for any response or suggestions. Appreciated. loess weathering 10-interglacial.x1t
  3. Is it possible to set a vertical flow instead of a horizontal flow direction in X1t?
  4. Dear Brian, How are you? I hope that you are doing very well. I am writing to you because I need your help with GWB. First of all, let me briefly describe my experiment. I have done column percolation tests using natural contaminated soil. I packed the contaminated soil (mainly with heavy metals) in a 5 cm diameter and 30 cm height acrylic column and permeated it with CaCl2 solution 1 mM at a flow rate of 12 mL/h (the flow direction is from bottom to top). I collected around 15 samples (leachate) within 3-month period and analyzed them by ICP and IC (ion chromatography). I input all leachate results in the GSS datasheet and would like to make solubility, speciation and transport modeling. I have the following questions: 1. In the GSS datasheet is there any place where I can input the TOC (total organic carbon) or DOC (dissolved organic carbon)? 2. In the GSS, how can I input Mo concentration? I know that there is no Mo information in the "thermo.dat", so, I changed it to "thermo.com.v8.r6t", but I am still not able to add Mo (I can't find it in "+analyte" > "basic species"). Did I do something wrong? 3. Do I have to know the specie of elements in advance? For example, from ICP analysis, I got the results of total Fe. In GSS, can I choose for example "Fe+++" and then choose the unit "mg/L (as Fe)" and solve the problem of choosing between "Fe++" and "Fe+++"? Another example is regarding B concentration, can I choose the specie "B(OH)3" and then select the unit "mg/L (as B)". One more example is "AsO4--", I think this is the only specie included in "thermo.dat", so I chose it and set as "mg/L (as As)". Is that the correct way to input the data in GSS or should I know the accurate specie since the beginning? 4. Regarding Xt1 transport, I would like to simulate/model the release of elements such as As, Pb, B, etc. and then plot or add the results I obtained from experiments. I have the following questions about what to input in each section: a. "Initial" section: should I input the mineral composition or elemental composition of the soil and the concentration of the permeating solution (CaCl2)? b. "Reactants" section: Should I input the mineral composition of the soil? c. "Inlet" section: Should I input the concentration of the permeating solution (CaCl2)? d. "Domain" section: Do you recommend me to use "linear" type or "spherical" (r1 = r2)? e. "Medium" section: Do I input the diffusion coefficient of the element, the porosity of the soil and the dispersivity of the element I am monitoring? I am very sorry for asking so many questions. Thank you very much in advance for your help. Angelica
  5. HI everyone, I am working on simulating basalt weathering. I wish to show with the help of GWB that: 1) Basalt weathers directly to kaolinite under slightly acidic conditions and flowing water 2) Basalt weathers to smectite under slightly acidic conditions and/or stagnant water condition 3) Smectite formed in turn again weathers to kaolinite under acidic flowing water conditions All above are facts and I would just like to show these conditions using GWB simulations. Following are the steps taken to do the same: 1) Inlet Pane: Rainwater composition 2) Reactant pane: Albite, Anorthite, K-feldspar, Diopside, Fayalite, Quartz voloume % specified as found in basalt. The rate constants, Specific surface area and nucleus density provided for all the above mentioned minerals as well as for Kaolinite and Smectite-low-Fe-Mg. 3) Initial pane: same as inlet 4) Domain pane: Linear with 1m x 1m x 1m volume of rock, discharge = 1m/year, 100 nodes 5) Medium pane: Porosity = 5% Problems faced: 1) Should initial = inlet? I am a bit confused by the "SOIL WEATHERING" example in Geochemical and Biogeochemical Reaction Modeling book by Dr. C. Bethke. Shouldn't the initial condition be the rock composition and the inlet be the rainwater composition? 2) I am getting result only in case of Albite % = 80-90, rest all composition combinations are either not converging or there is excessive charge imbalance or decrease in porosity at "node 1" 3) Even if I am taking Anorthite or Diopside as 90 volume % and nothing else, I am not getting results. I would be very grateful to you if you can guide me through solving my problem statement. > time start = 0 day, end = 1 yr > width = 1 m > height = 1 m > Nx = 100 > discharge = 1 m/yr > porosity = .05 > dispersivity = 1 cm > scope = initial > H2O = 1 free kg > HCO3- = .1 mg/l > pH = 7 > Na+ = 2 mg/l > Cl- = 3.8 mg/l > balance on Cl- > K+ = .3 mg/l > Mg++ = .3 mg/l > Ca++ = .1 mg/kg > SO4-- = .6 mg/l > O2(aq) = 7 mg/kg > Al+++ = 1 ug/kg > SiO2(aq) = 1 ug/kg > Fe++ = 1 ug/kg > scope = inlet > H2O = 1 free kg > HCO3- = .1 mg/l > pH = 7 > Na+ = 2 mg/l > Cl- = 3.8 mg/l > balance on Cl- > K+ = .3 mg/l > Mg++ = .3 mg/l > Ca++ = .1 mg/l > SO4-- = .6 mg/l > O2(aq) = 7 mg/kg > Al+++ = 1 ug/kg > SiO2(aq) = 1 ug/kg > Fe++ = 1 ug/kg > fix fugacity of CO2(g) > kinetic K-feldspar rate_con = 3e-17 surface = 1000 nucleus = 4000 > kinetic Albite 25 volume% rate_con = 1e-16 surface = 1000 > kinetic Quartz 2 volume% rate_con = 4.2e-18 surface = 1000 nucleus = 4000 > kinetic Kaolinite rate_con = 1e-17 surface = 1e5 nucleus = 4000 > kinetic Gibbsite rate_con = 5e-17 surface = 4000 nucleus = 4000 > kinetic Anorthite 20 volume% rate_con = 3.16e-8 surface = 1000 nucleus = 4000 > kinetic Diopside 25 volume% rate_con = 4.36e-11 surface = 600 nucleus = 4000 > kinetic Fayalite 5 volume% rate_con = 1.58e-5 surface = 1000 > kinetic Smectite-low-Fe-Mg rate_con = 1.05e-15 surface = 6.1e5 nucleus = 4000 > precip = off Thank you. Basalt_Weathering.x1t
  6. Hello, I'm constructing a 1D reactive transport model where fluid flows through sandstone. I consistently get this (or, similar) message: Solving for composition of inlet fluid. Solving for initial state of each nodal block. Residuals too large, 652-th interation Largest residual(s): Resid Resid/Totmol Cbasis -------------------------------------------------------- Cl- 190.2 1.207e+200 1.031e-196 -------------------------------------------------------- I ran SpecE8 on both initial and inlet fluid compositions, and they both are about charge balanced: * Initial: Charge imbalance = -0.012 meq/kg (-0.001151% error); * inlet: Charge imbalance = -0.005351 meq/kg (-0.0005109% error) I also ran React on the inlet fluid composition reacting with quartz, calcite, K-feldspar, and hematite, and this calculation has converged. Please let me know if you have any ideas of how to set up this 1D reactive flow model. Thank you, Anastasia
  7. I would like to utilize the mulitcore capabilities of GWB v. 8+, and while reading about this feature in the GWB transport manual, I became curious as to how the parallel algorithm actually subdivides the domain. I understand that the domain is broken into threads of m blocks, each containing n nodes. Each core handles a block, m, but I am wondering how the nodes the physical and chemical data are transferred between m1, m2, m3, etc. I think that with the Operator Splitting Method all transport terms are solved first, mobile species are redistributed, then the ensuing chemical reaction terms are evaluated. Obviously the spatial arrangement of the nodes matters, so how will the nodes in block m1 share data with m2, m3, etc? And how can I be sure that mass and charge balance are preserved?
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