Process demos  Process demos  Delft3D
Process demos
Below, 5 different model demo's can be downloaded which are described at the bottom of this page. These demo's showcase different aspects of the Delft3D software package. Each demo holds four folders:
Input: contains all model input files
Output: contains all model ouput files that are created when the model is run
Measurements: contains measurements or analytical solutions used to validate the demo results
Plots: contains Muppet input files used to create the plots
When you download the files, make sure you store them in the same folder structure (otherwise, Muppet plots won't work)
The plots have been created using Muppet, which you can download for free. This application requires the installation of Matlab Compiler Runtime (MCR). Please be aware that you need different versions of the MCR for 32bit (download) and 64bit (download).
DEMO 1: Migrating trench in a 1D channel
Description In this demo, water flows across a steepsided trench cut in the sand bed of a flume. The water reaches the upstream edge of the trench with an equilibrium suspended sediment concentration profile. As the flow decelerates over the deeper trench some sediment is deposited. Sediment is then picked back up by the accelerating flow at the downstream edge of the trench. Due to the spatial difference between the areas of deposition and erosion the trench appears to migrate downstream. Initially the model has a constant depth with a trench with vertical walls in the middle of the model area. The goal is to verify whether the trench development due to morphological impact is in agreement with measurements carried out by Van Rijn (1984). The computed results of Delft3DFLOW as well as the measurements are presented in the Muppet plot. Model characteristics


DEMO 2: Simple channel flow
Description Flow in a simple channel with sloping bathymetry is investigated. A steady solution is reached, in which the vertical viscosity term balances the barotropic pressure gradient. For this steady situation an analytical solution is available from the 2D shallow water equations. Results from Delft3DFLOW simulations are compared to the analytical solution. For the 3D simulations vertical profiles for velocity are investigated. Solutions are obtained with the k epsilon turbulence model. It is validated whether the models produces logarithmic velocity profiles. A comparison has been made between sigmalayer and with Zlayer model results. The formulas that have been used to obtain the analytical solutions are presented in a document in the measurements folder (Genseberger et al., 2002). Both the full document (testcasesZmodelD3Dflow.pdf) as well as the relevent part for this demo (Simple channel flow analytical solutions.pdf) can be found. Model characteristics


DEMO 3: Tidal flume
Description The model is used to simulate salt intrusion in a river using both sigma and Z  layers. A salt tidal signal enters the model from the west. the model tries to reproduce measurements that have been carried out at Deltares. The scale model of the tidal flume has a basin with a surface area of 120 m2, representing a sea, and a flume with a width of 1 m and a length of 130 m, representing a river. In the numerical simulation, we use a schematisation of the river (130 x 1 grid cells of 1 x 1 m2 each). At the sea side a water level boundary is applied.
Model characteristics


DEMO 4: Wave driven longshore current
Description In this demo, both the FLOW and WAVE module of Delft3D are showcased. This model reproduces a longshore current that is the effect of constant obliquely incident waves. The waves enter the model domain under an angle and propagate towards the shore. When the waves start to break, a longshore current is generated as the alongshore current is a function of the dissipation of the wave energy. This demo does not reproduce any analytical or measured values. Model characteristics


DEMO 5: Wind driven channel flow
Description For the wind induced flow in a straight channel analytical solutions are available [Kocyigit and Falconer, 2004] The paper can be found in the measurements folder. A comparison is made between the analytical solutions in these publications and results obtained with Delft3DFLOW. This is done for the water levels and vertical velocity profiles. The analytical solution presented by Kocyigit and Falconer reads:
in which zeta is the water level, tau is the wind shear stress, rho is the water density, g is acceleration due to gravity, h is the water depth, Vv is the vertical eddy viscosity, k1 is a linearised bottom friction coefficient and u is the horizontal velocity. Kocyigit and Falconer specified the following conditions and parameters:
In Delft3DFLOW one can not specify the wind shear stress, but only the friction coefficient. The latter is determined using:
where rho is the air density, cdw is the friction coefficient and u is wind velocity. Wind speeds of 5 and 10 m/s and tau values of 0.1 and 0.235 N/m2 respectively were specified by Kocyigit and Falconer. Using the abovedescribed, friction coefficients cdw should be 0.004 and 0.00325, respectively, in order to arrive at the wind stresses of Kocyigit and Falconer. In this way, the simulations of Kocyigit and Falconer are reproduced with Delft3DFLOW.
A same approach is followed for the linear bottom friction coefficient k1. In Delft3DFLOW the bottom roughness is prescribed in a different way. The standard approach is the (2D) Chézy coefficient. In Delft3DFLOW this value is converted in a 3D friction coefficient in case of 3D modelling. A 2D Chézy roughness of 30 m1/2/s is applied in case of a wind speed of 5 m/s, which corresponds to a k1 value of 0.005 m/s. In case of a wind velocity of 10 m/s, a Chézy value of 35 m1/2/s is used. We remark that the two simulations (wind speed of 5 or 10 m/s) yields different bottom currents. In order to meet the linear bottom friction coefficient k1, different Chézy values have to be applied.
model characteristics
The difference in Chézy values for the two test cases can be subscribed to the conversion from a 2D to a 3D Chézy value in Delft3DFLOW. The resulting bottom friction stresses were compared to make sure identical bottom boundary conditions were applied. To this end the second test case requires a Chézy value of 35 m1/2/s.

