|
Research
Areas
Thanos's Interdisciplinary approach at UI |
|
| |
Thanos's project areas
Sediment Transport |
Cohesive Sediment: Understanding the
mechanisms involved in the transport and fate of cohesive sediment in
natural channel systems along with effects on aquatic organisms remains
an open case in water-related engineering disciplines. The main
challenge is that cohesive sediment dynamics are controlled not only by
physical forces (e.g., inertia, buoyancy, drag, lift, friction) but also
by electrochemical forces. A complete identification of the
properties of cohesive sediments typically involves twenty-four
parameters (Commission of the European Community) and explains why the
few studies referring to the transport and fate of cohesive sediment are
site-specific rather than have a more fundamental nature. |
Applications:
- Contamination
- Bank Erosion
- Fluidization
- Channelling
|
Noncohesive Sediment: Understanding the mechanisms involved
in the transport and fate of noncohesive soils in natural channel
systems remains an open case in water-related engineering disciplines.
The main challenge in studying noncohesive sediments is the complex
character of the bed geometry which governs the velocity, as well as the
turbulence structure of the flow which in turn, control the
sediment-carrying capacity of the flow. Bed geometry is controlled by
stochastic processes and subject to drastic changes due to changes in
the flow condition. Bedforms, clusters, step and
pools are few examples of such complicated bed geometry. In
addition, sediment may consist of a wide range of grain sizes.
|
Applications:
- Incipient of motion
- Virtual Velocity
-
Step-pool Configurations
-
Cluster and Relative Submergence Studies
- Suspended Load
|
Hydrodynamic/Sediment Transport models |
One-dimensional models:
Since the early 1980s, 1-D models
have been used with some success in research and engineering practice.
Most of the 1-D models are formulated in a rectilinear coordinate system
and solve the differential
conservation equations of mass and
momentum of flow (the St. Venant flow equations) along with the sediment mass continuity
equation (the Exner equation) using finite-difference schemes.
|
Applications:
-
Modeling Mountain Streams
-
Modeling Rills
|
Two-dimensional models:
Since the early 1990s, there has been
a shift in computational research towards 2-D models. Most of the 2-D
models are currently available to the hydraulic engineering community as
interface-based software in order to allow easy data input and
visualization of results. This added capability has made these models
user friendly and popular. 2-D models are depth-averaged models that
can provide spatially varied information about water depth and bed
elevation within rivers, lakes and estuaries and the magnitude of
depth-averaged streamwise and transverse velocity components. Most of
2-D models solve the depth-averaged continuity and Navier-Stokes
equations along with the sediment mass balance equation via the methods
of finite-difference, finite-element or finite-volume.
|
Applications:
-
Simulation of in-stream sediment capture
structures
-
Black Lake simulation
|
Three-dimensional models:
In many hydraulic engineering
applications one has to resource to 3-D models when 2-D models are not
suitable to describe certain hydrodynamic/sediment transport processes.
Flows in the vicinity of piers and near hydraulic structures are
examples where 3-D flow structures are ubiquitous and 2-D models in this
case do not adequately represent the physics. With the latest
developments in computing technology such as computational speed,
parallel computing and data storage classification, 3-D
hydrodynamic/sediment transport models have become much more attractive
to use comparatively to ten years ago. The majority of the 3-D models
solve the continuity and the Navier-Stokes equations along with the
sediment mass balance equation via the methods of finite-difference,
finite-element or finite-volume. The Reynolds Average Navier-Stokes
(RANS) approach has been employed to solve the governing equations.
|
Applications:
-
Flow heterogeneity over 3D cluster microform
|
Hydraulic Structures |
Design and evaluation:
Hydraulic structures are typically used for
flood control, flood conveyance, irrigation purposes, fish passage,
banks protection, navigation, recreation and ecological restoration. A
hydraulic structure must meet the safety, functional and aesthetic goals
for its purpose. Thus, valuation studies must be carried out before and
after the construction of the structure to assess its impacts. The
structure must be of sufficient size that natural flooding is not
worsened and to ensure that the structure can withstand the design flood
and remain traversable. This is required in order to protect the
property and residents upstream and downstream of a structure. In the
hydraulic design, one main thing to remember is that water is dynamic.
|
Applications:
-
Effectiveness of grate
- Fish screen
- Fish Passage
- Culvert design
-
Steep stream restoration model
- Shallow water habitat in the Missouri River
-
Black Lake restoration
|
Watershed Studies |
Watershed dynamics:
Many watershed simulations today work in the
batch world; an event is simulated based on a static set of field data.
If newer data become available, the simulation is simply rerun. For
example, hydrodynamic and sediment transport simulations to predict
geomorphologic changes within a stream and the impact of these changes
to the aquatic life are conducted by considering a constant sediment
input value from terrestrial sources such as roads, floodplains, and
other natural occurring disturbances (i.e., landslides, fires). As a
result perturbations that exist in the system due to the spatial and
temporal variability in the terrestrial sediment input are not
accounted. Very few applications use real time data even if the
capability to do so is available. A great effort has been recently
devoted to run simulations faster than real time based on static data
sets. However, this is highly inefficient and leads to multiple
sediment predictions that are conflicting when major events are
predicted. This lack of ability to dynamically inject data into
simulations and other applications, as these applications execute,
limits the analysis and the predictive capabilities of these
applications. The novel capabilities to be sought here are application
simulations that can dynamically accept and respond to on-line field
data and measurements and/or control such measurements. This
synergistic and symbiotic feedback control-loop between simulations and
measurements is a novel technical direction that can open domains in the
capabilities of simulations within watersheds that can facilitate the
“capturing” of episodic catastrophic events.
|
Applications:
- Development of a watershed testbed
- Runoff
-
Infiltration and water quality
- Microtopography
-
Biogeochemical Fingerprinting and Isotopes
|
Watershed modeling: Watershed
related processes are non-linear in nature due to complex interactions
in pedology, geology, biology and hydrology and remain all-together a
challenging problem with several societal implications. Some of the
perplex questions associated with watershed processes are the effects of
scale in monitoring and modeling, the integration of all phases (i.e.,
surface and subsurface) in monitoring and modeling, and the development
of economic and environmental indicators for alternative scenarios and
modeling assessment purposes. Recognizing
the critical need for developing an integrated and scientifically sound
framework in watershed research, interdisciplinary groups began to
emerge, beyond traditional discipline, some innovative concepts
for watershed modeling.
|
Applications:
- Modeling technologies
- Digital watershed
- Modeling the Upper South Amana sub-watershed
- Modeling the Red River watershed
- Modeling the Jerome Creek sub-watershed
|
