I have been rewriting this part completely new in C++. So at the moment a lot of the following is out of date.
Culvert at dike To discharge water from island to sea
Pumping station with pipes To discharge water from island to sea
Discharge water to Pumping-station of culvert at dike
Weirs To control waterlevel ditch
Culvert in ditch When ditch has to cross road
Lakes / surface water For storage of surplus of rainfall
Storage settling basin (BBB)
The dynamic water system on land is programmed as a blueprint. FD_Surfacewater contains both the logic and the assets of the water system. The backbone of the FD_Surfacewater is a spline with points. The points represent a change in the water system, for example: input discharge, different structure (pipe, channel, weir..), different dimension. So each point (=Node) is connected with the database WaterSystemData. So in between 2 points (=branch) of the backbone spline, everything is the same, based on the information of the downstream point.. Spline and point represent the bedlevel of the structure. Index 0 spline is downstream
Al the programming is done in the so called construction script. This is a cool feature of Unreal Engine. Al programmed calculations can be done in the editor. It is for example not necessary to run the game, to see what waterlevels will occur. They are already calculated in the editor.
The basis of the watersystem is a spline. Between 2 nodes the structure is the same. The location of the spline is the bedlevel.
A FD_Surfacewateris one line with no branches and has a fixed direction of flow.
A dendritic system is possible, because the 3D world may contain different FD_Surfacewaterwhich are connected at points. When calculation a dendritic system the sequence of making calculations is important.
Strategy for calculating the water-system.We assume a stationary flow. So new calculations are only made when changes are made to the water-system. In the future calculations will be made per time-step and change in storage will also be taken into account. Link to page with formulas used
Internal Unreal uses centimeters, the FD_Surfacewater uses m
Backbone of FD_Surfacewater is the WaterDataStruct which stores all data (also calculated data) for each branch.
Connect side branches
Information on side branch is stored in [ConnectionLeft] and/or [ConnectionRight]
In FD_GameMode: FD_WaterSystemsref and FD_WatersystemName. Note This does not work in constructionscript ? So it should be a separate function in the constructionscript.
New function Find_Side_Branches
Changed variable InputDischarge to a 2dvector. x = de input branch, y is the input from sidebranches
Design Manhole / Sewer
If 2 pipes don’t have the same bedlevels, the difference in height is stored in With_Diameter_m.y. Adding this height is only applied the x downstreampoint
Manhole is not a separate branch, but is generated when 2 culvert pipes branches connect.
The check on manhole is made when type is culvert. If type_down also is a culvert, a manhole can be added.
Switch to add manhole is : When diameter pipes is different, manhole is added automatically When diameter pipes are the same, the following switch is used. Slope X = 1 add manhole, Slope X = 0 no manhole
A Boolean variable Manhole is defined.
Manhole is always a rectangle, with max 4 pipes connected. So 2 other BP_watersytems could be connected to the manhole.
Alle dimensions in m
When function manhole is activated the following information is defined: – bedlevel, based on 4 connections – D1, D2 (left), D3, D4(right) – Width manhole based on D1 and D4. Width = Max D1 / D3 + 0,6 m – Length manhole based on D2 en D4. Length = Max D2 / D4 + 0,6 m – Length manhole / 2 = reduction length (m) – Surfacelevel is de highest surfacelevelworld of the 4 connections
Manhole is activated before the pipe is drawn. This because the reduction length.
Information from the array is also necessary for the Reduction Length for ending and starting pipe.
Flow is turbulent. So formulas of Manning, Chezy and Darcy-Weisbach can be used.
Flow is sub-critical. So calculations of water-levels start downstream and goes upstream. At weirs super-critical flow may occur.
Flow is steady Discharge is not changing rapidly. Of-course over time discharge (and thus water-levels etc) can change.
Sea is salt water, on the island fresh water
There are two main watersystems. The watersystem on the island and the sea (waves, tide, current). The connection between the two are by the culvert in the dike and seepage. High tide in combination with low water level on the island could make water flow from sea to the island. High tide can cause seepage to the land, low tide seepage to sea. Maybe in high tide in combination with big waves can cause water flowing over the dike to the island.
Water enters the systeem by: rainfall and seepage.
Water leaves the island through : Culvert in dike, pumping station, seepage and evapotranspiration.
System is dendritic. So water has one direction to flow.
Calculations in FD_watersystems
For each branch waterlevel (ylevel) and Energylevel (Hlevel) are calculated at the beginning (.x) and end (.y) of the branch. This info is stored in WatersystemData.
Hlevel.x = Hlevel.y downstream branch.
yLevel.x = yLevel.y downstream branch. Consequence of this strategy is that when there is a significant change in dimension or discharge, a short branche is needed. In this short branch the transfer between the 2 different velocityheads takes place. With change in discharge this short branch is located downstream, with change in dimension this short branch is located upstream
Weir is an exception. Hlevel.x is calculated based on the crestlevel.
Over the length of a branch, the basic dimensions are the same, only the surfacelevel at x and y may differ. Exception is the connector, you have different width and slope downstream and upstream!!
CulvertRectangle: If downstreams waterdepth < Height culvert : Type is converted to Trapezium. Note: With high velocities, water level will rise and the type maybe should be concerted back to culvertrectangle. This can be solved by splitting het culvert in several branches.
In a branch (between 2 points) discharge is always the same.
2 special branches when calculating. First is the outflow: Discharge = 0. Value in InputDischarge.x is the velocity in the receiving water. Second is the weir : There is a jump in HlevelWorld compared to the downstream waterlevel.
Weir is always assumed as free flow. And as a short crest. Waterlevel .x and .y are the same.
Based on ylevel.x. Slope Hline is calculated. Hlevel.y is calculated.