.. _dfnflow-chapter:

dfnFlow
========
*dfnFlow* involves using flow solver such as PFLOTRAN or FEHM. PFLOTRAN is recommended if a large number of fractures ( > O(1000)) are involved in a network. Using the function calls that are part of pydfnworks, one can create the mesh files needed to run PFLOTRAN. This will involve creating unstructured mesh file ``*uge`` as well as the boundary  ``*ex`` files. Please see the PFLOTRAN user manual at http://www.pflotran.org under unstructured *explicit* format usage for further details. An example input file for PFLOTRAN is provided in the repository. Please use this as a starting point to build your input deck.

Below is a sample input file. Refer to the PFLOTRAN user manual at http://www.pflotran.org for input parameter descriptions. 

.. code-block:: c

	# Jan 13, 2014
	# Nataliia Makedonska, Satish Karra, LANL
	#================================================

	SIMULATION
	  SIMULATION_TYPE SUBSURFACE
	  PROCESS_MODELS
	    SUBSURFACE_FLOW flow
	      MODE RICHARDS
	    /
	  /
	END
	SUBSURFACE

	DFN

	#=========================== discretization ===================================
	GRID
	  TYPE unstructured_explicit full_mesh_vol_area.uge 
	  GRAVITY 0.d0 0.d0 0.d0
	END


	#=========================== fluid properties =================================
	FLUID_PROPERTY
	  DIFFUSION_COEFFICIENT 1.d-9
	END

	DATASET Permeability
	  FILENAME dfn_properties.h5
	END

	#=========================== material properties ==============================
	MATERIAL_PROPERTY soil1
	  ID 1
	  POROSITY 0.25d0
	  TORTUOSITY 0.5d0
	  CHARACTERISTIC_CURVES default
	  PERMEABILITY
	    DATASET Permeability
	  /
	END


	#=========================== characteristic curves ============================
	CHARACTERISTIC_CURVES default
	  SATURATION_FUNCTION VAN_GENUCHTEN
	    M 0.5d0
	    ALPHA  1.d-4
	    LIQUID_RESIDUAL_SATURATION 0.1d0
	    MAX_CAPILLARY_PRESSURE 1.d8
	  /
	  PERMEABILITY_FUNCTION MUALEM_VG_LIQ
	    M 0.5d0
	    LIQUID_RESIDUAL_SATURATION 0.1d0
	  /
	END

	#=========================== output options ===================================
	OUTPUT
	  TIMES s 0.01 0.05 0.1 0.2 0.5 1
	#  FORMAT TECPLOT BLOCK
	  PRINT_PRIMAL_GRID
	  FORMAT VTK
	  MASS_FLOWRATE
	  MASS_BALANCE
	  VARIABLES
	    LIQUID_PRESSURE
	    PERMEABILITY
	  /
	END

	#=========================== times ============================================
	TIME
	  INITIAL_TIMESTEP_SIZE  1.d-8 s
	  FINAL_TIME 1.d0 d==
	  MAXIMUM_TIMESTEP_SIZE 10.d0 d
	  STEADY_STATE
	END

	# REFERENCE_PRESSURE 1500000.

	#=========================== regions ==========================================
	REGION All
	  COORDINATES
	    -1.d20 -1.d20 -1.d20
	    1.d20 1.d20 1.d20
	  /
	END 

	REGION inflow
	  FILE pboundary_left_w.ex
	END

	REGION outflow
	  FILE pboundary_right_e.ex
	END

	#=========================== flow conditions ==================================
	FLOW_CONDITION initial
	  TYPE
	     PRESSURE dirichlet 
	  /
	  PRESSURE 1.01325d6
	END


	FLOW_CONDITION outflow 
	  TYPE 
	     PRESSURE dirichlet
	  /
	  PRESSURE 1.d6
	END

	FLOW_CONDITION inflow
	  TYPE
	    PRESSURE dirichlet
	  /
	  PRESSURE 2.d6
	END

	#=========================== condition couplers ===============================
	# initial condition
	INITIAL_CONDITION
	  FLOW_CONDITION initial
	  REGION All
	END


	BOUNDARY_CONDITION INFLOW 
	  FLOW_CONDITION inflow
	  REGION inflow
	END

	BOUNDARY_CONDITION OUTFLOW
	  FLOW_CONDITION outflow 
	  REGION outflow
	END

	#=========================== stratigraphy couplers ============================
	STRATA
	  REGION All 
	  MATERIAL soil1
	END

	END_SUBSURFACE